Exclude reporter from receiving notifications from their own reports.

Currently only works if the reporting actor is an admin, but if we include
moderators with those who receive notification reports it will work for them.

lib/pleroma/notification.ex

@@ -507,8 +507,8 @@ def get_potential_receiver_ap_ids(%{data: %{"type" => "Follow", "object" => obje
     [object_id]
   end
 
-  def get_potential_receiver_ap_ids(%{data: %{"type" => "Flag"}}) do
-    User.all_superusers() |> Enum.map(fn user -> user.ap_id end)
+  def get_potential_receiver_ap_ids(%{data: %{"type" => "Flag", "actor" => actor}}) do
+    (User.all_superusers() |> Enum.map(fn user -> user.ap_id end)) -- [actor]
   end
 
   def get_potential_receiver_ap_ids(activity) do

lib/pleroma/web/activity_pub/activity_pub.ex

@@ -377,6 +377,7 @@ defp do_flag(
          :ok <-
            maybe_federate(stripped_activity) do
       User.all_superusers()
+      |> Enum.filter(fn user -> user.ap_id != actor end)
       |> Enum.filter(fn user -> not is_nil(user.email) end)
       |> Enum.each(fn superuser ->
         superuser