Use full URL of user avatar on webhook push

lib/gitlab/data_builder/push.rb

@@ -86,7 +86,7 @@ module Gitlab
           user_name: user.name,
           user_username: user.username,
           user_email: user.email,
-          user_avatar: user.avatar_url,
+          user_avatar: user.avatar_url(only_path: false),
           project_id: project.id,
           project: project.hook_attrs,
           commits: commit_attrs,