Remove superfluous actor key suffix

Fragments are already always stripped anyway
so listing one specific fragment here is
unnecessary and potentially confusing.

This effectively reverts
4457928e32
but keeps the added bridgy testcase.

lib/pleroma/signature.ex

@@ -10,7 +10,7 @@ defmodule Pleroma.Signature do
   alias Pleroma.User
   alias Pleroma.Web.ActivityPub.ActivityPub
 
-  @known_suffixes ["/publickey", "/main-key", "#key"]
+  @known_suffixes ["/publickey", "/main-key"]
 
   def key_id_to_actor_id(key_id) do
     uri =