Fix test in- and exclusion

We had a feww files matching neither inclusion nor exclusion rules.
With elixir 1.19 this creates a warning.
Most were intended to be ignored and thus we now override the default
rules in mix.exs to be explicit about this. However, two test files were
simply misnamed and intended to run, but untill now skipped.

Notably, the signing key test for shared key ids currently fails due to
a missing mock. For now this faulty test is simply disabled, the next
commit will fix it

mix.exs

@@ -13,6 +13,7 @@ defmodule Pleroma.Mixfile do
       aliases: aliases(),
       deps: deps(),
       test_coverage: [tool: ExCoveralls],
+      test_ignore_filters: [~r/_helper.exs$/, ~r/^test\/fixtures\//, ~r/^test\/credo\//],
       # Docs
       name: "Akkoma",
       homepage_url: "https://akkoma.dev/",

test/pleroma/user/signing_key_test.exs

@@ -233,6 +233,7 @@ defmodule Pleroma.User.SigningKeyTests do
     assert user.signing_key.key_id == refreshed_org_key.key_id
   end
 
+  @tag :skip
   test "remote users sharing signing key ID don't break our database" do
     # in principle a valid setup using this can be cosntructed,
     # but so far not observed in practice and our db scheme cannot handle it.