Cachex: Unify arity of callback function

lib/pleroma/user.ex

@@ -1091,7 +1091,7 @@ defmodule Pleroma.User do
   def get_cached_by_nickname(nickname) do
     key = "nickname:#{nickname}"
 
-    @cachex.fetch!(:user_cache, key, fn ->
+    @cachex.fetch!(:user_cache, key, fn _ ->
       case get_or_fetch_by_nickname(nickname) do
         {:ok, user} -> {:commit, user}
         {:error, _error} -> {:ignore, nil}

lib/pleroma/web/mastodon_api/controllers/poll_controller.ex

@@ -57,7 +57,7 @@ defmodule Pleroma.Web.MastodonAPI.PollController do
   defp get_cached_vote_or_vote(user, object, choices) do
     idempotency_key = "polls:#{user.id}:#{object.data["id"]}"
 
-    @cachex.fetch!(:idempotency_cache, idempotency_key, fn ->
+    @cachex.fetch!(:idempotency_cache, idempotency_key, fn _ ->
       case CommonAPI.vote(user, object, choices) do
         {:error, _message} = res -> {:ignore, res}
         res -> {:commit, res}