Pleroma.Web.ActivityPub.Builder: fix dialyzer error

lib/pleroma/web/activity_pub/builder.ex:115:pattern_match
The pattern can never match the type.

Pattern:
_emojo = %{:file => _path}

Type:
nil | binary()

lib/pleroma/emoji.ex

@@ -51,12 +51,12 @@ def reload do
   end
 
   @doc "Returns the path of the emoji `name`."
-  @spec get(String.t()) :: String.t() | nil
+  @spec get(String.t()) :: Emoji.t() | nil
   def get(name) do
     name = maybe_strip_name(name)
 
     case :ets.lookup(@ets, name) do
-      [{_, path}] -> path
+      [{_, emoji}] -> emoji
       _ -> nil
     end
   end