This simple addon will allow you to set which usergroups have the permission to upload gif avatars. Gif avatars are typically animated and many admins don't like all users to have them.
This is a screenshot of the usergroup setting:
If a user tries to upload a gif avatar, and they do not have the proper permission, they will get a error message:
This is a screenshot of the usergroup setting:
If a user tries to upload a gif avatar, and they do not have the proper permission, they will get a error message: