Use standard-compliant Accept header when fetching

Spec says clients MUST use this header and servers MUST respond to it,
while servers merely SHOULD respond to the one we used before.
https://www.w3.org/TR/activitypub/#retrieving-objects

Fixes: AkkomaGang/akkoma#730

lib/pleroma/object/fetcher.ex

@@ -324,7 +324,7 @@ defmodule Pleroma.Object.Fetcher do
     date = Pleroma.Signature.signed_date()
 
     headers =
-      [{"accept", "application/activity+json"}]
+      [{"accept", "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\""}]
       |> maybe_date_fetch(date)
       |> sign_fetch(id, date)
 

test/support/http_request_mock.ex

@@ -5,7 +5,10 @@
 defmodule HttpRequestMock do
   require Logger
 
-  def activitypub_object_headers, do: [{"content-type", "application/activity+json"}]
+  def activitypub_object_headers,
+    do: [
+      {"content-type", "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\""}
+    ]
 
   def request(
         %Tesla.Env{
@@ -97,7 +100,10 @@ defmodule HttpRequestMock do
          File.read!("test/fixtures/users_mock/masto_featured.json")
          |> String.replace("{{domain}}", "mastodon.sdf.org")
          |> String.replace("{{nickname}}", "rinpatch"),
-       headers: [{"content-type", "application/activity+json"}]
+       headers: [
+         {"content-type",
+          "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\""}
+       ]
      }}
   end
 
@@ -208,7 +214,7 @@ defmodule HttpRequestMock do
         "https://mst3k.interlinked.me/users/luciferMysticus",
         _,
         _,
-        [{"accept", "application/activity+json"}]
+        [{"accept", "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\""}]
       ) do
     {:ok,
      %Tesla.Env{
@@ -231,7 +237,7 @@ defmodule HttpRequestMock do
         "https://hubzilla.example.org/channel/kaniini",
         _,
         _,
-        [{"accept", "application/activity+json"}]
+        [{"accept", "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\""}]
       ) do
     {:ok,
      %Tesla.Env{
@@ -241,7 +247,9 @@ defmodule HttpRequestMock do
      }}
   end
 
-  def get("https://niu.moe/users/rye", _, _, [{"accept", "application/activity+json"}]) do
+  def get("https://niu.moe/users/rye", _, _, [
+        {"accept", "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\""}
+      ]) do
     {:ok,
      %Tesla.Env{
        status: 200,
@@ -250,7 +258,9 @@ defmodule HttpRequestMock do
      }}
   end
 
-  def get("https://n1u.moe/users/rye", _, _, [{"accept", "application/activity+json"}]) do
+  def get("https://n1u.moe/users/rye", _, _, [
+        {"accept", "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\""}
+      ]) do
     {:ok,
      %Tesla.Env{
        status: 200,
@@ -270,7 +280,9 @@ defmodule HttpRequestMock do
      }}
   end
 
-  def get("https://puckipedia.com/", _, _, [{"accept", "application/activity+json"}]) do
+  def get("https://puckipedia.com/", _, _, [
+        {"accept", "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\""}
+      ]) do
     {:ok,
      %Tesla.Env{
        status: 200,
@@ -343,7 +355,7 @@ defmodule HttpRequestMock do
   end
 
   def get("https://mobilizon.org/events/252d5816-00a3-4a89-a66f-15bf65c33e39", _, _, [
-        {"accept", "application/activity+json"}
+        {"accept", "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\""}
       ]) do
     {:ok,
      %Tesla.Env{
@@ -353,7 +365,9 @@ defmodule HttpRequestMock do
      }}
   end
 
-  def get("https://mobilizon.org/@tcit", _, _, [{"accept", "application/activity+json"}]) do
+  def get("https://mobilizon.org/@tcit", _, _, [
+        {"accept", "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\""}
+      ]) do
     {:ok,
      %Tesla.Env{
        status: 200,
@@ -417,7 +431,7 @@ defmodule HttpRequestMock do
   end
 
   def get("http://mastodon.example.org/users/relay", _, _, [
-        {"accept", "application/activity+json"}
+        {"accept", "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\""}
       ]) do
     {:ok,
      %Tesla.Env{
@@ -428,7 +442,7 @@ defmodule HttpRequestMock do
   end
 
   def get("http://mastodon.example.org/users/gargron", _, _, [
-        {"accept", "application/activity+json"}
+        {"accept", "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\""}
       ]) do
     {:error, :nxdomain}
   end
@@ -620,7 +634,9 @@ defmodule HttpRequestMock do
      }}
   end
 
-  def get("https://mstdn.io/users/mayuutann", _, _, [{"accept", "application/activity+json"}]) do
+  def get("https://mstdn.io/users/mayuutann", _, _, [
+        {"accept", "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\""}
+      ]) do
     {:ok,
      %Tesla.Env{
        status: 200,
@@ -633,7 +649,7 @@ defmodule HttpRequestMock do
         "https://mstdn.io/users/mayuutann/statuses/99568293732299394",
         _,
         _,
-        [{"accept", "application/activity+json"}]
+        [{"accept", "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\""}]
       ) do
     {:ok,
      %Tesla.Env{
@@ -779,7 +795,7 @@ defmodule HttpRequestMock do
         "http://gs.example.org:4040/index.php/user/1",
         _,
         _,
-        [{"accept", "application/activity+json"}]
+        [{"accept", "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\""}]
       ) do
     {:ok, %Tesla.Env{status: 406, body: ""}}
   end
@@ -966,7 +982,9 @@ defmodule HttpRequestMock do
      }}
   end
 
-  def get("https://social.heldscal.la/user/23211", _, _, [{"accept", "application/activity+json"}]) do
+  def get("https://social.heldscal.la/user/23211", _, _, [
+        {"accept", "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\""}
+      ]) do
     {:ok, Tesla.Mock.json(%{"id" => "https://social.heldscal.la/user/23211"}, status: 200)}
   end
 
@@ -1207,12 +1225,15 @@ defmodule HttpRequestMock do
          File.read!("test/fixtures/users_mock/masto_featured.json")
          |> String.replace("{{domain}}", "lm.kazv.moe")
          |> String.replace("{{nickname}}", "mewmew"),
-       headers: [{"content-type", "application/activity+json"}]
+       headers: [
+         {"content-type",
+          "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\""}
+       ]
      }}
   end
 
   def get("https://info.pleroma.site/activity.json", _, _, [
-        {"accept", "application/activity+json"}
+        {"accept", "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\""}
       ]) do
     {:ok,
      %Tesla.Env{
@@ -1227,7 +1248,7 @@ defmodule HttpRequestMock do
   end
 
   def get("https://info.pleroma.site/activity2.json", _, _, [
-        {"accept", "application/activity+json"}
+        {"accept", "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\""}
       ]) do
     {:ok,
      %Tesla.Env{
@@ -1242,7 +1263,7 @@ defmodule HttpRequestMock do
   end
 
   def get("https://info.pleroma.site/activity3.json", _, _, [
-        {"accept", "application/activity+json"}
+        {"accept", "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\""}
       ]) do
     {:ok,
      %Tesla.Env{