Remove the elevenlabs extension

[oobabooga]

Now that coqui_tts generates high-quality speech offline through the XTTSv2 model, I do not see the point in keeping an extension that promotes a commercial API service.

It also adds dependencies that increase the installation time and size for the project.

People who wish to keep using this extension can simply return to a past commit with git checkout, copy the extensions/elevenlabs_tts folder, and place it back in the extensions/ folder.

[madschristensen99]

Elevenlabs offers services that are not as good as coqui, such as custom voice models

[madschristensen99]

Please undo this change I use elevenlabs all the time

[311-code]

I think this was a mistake as the coqui-tts still doesn't come close to the elevenlabs v2 voices, I even updated the code and sent it to you on discord for full V2 cloned voices support. I don't get it.