Clean up setup.py
# What does this PR do?

This PR cleans up a bit the README in two ways:
- Remove support for Python 3.6 as we said the current release was the last one with Python 3.6
- Clean up a bit the authors field, description and keywords to emphasize the multimodal support.

Since the Hugging Face team is growing, I propose to replace the authors field by something more generic than adding names, let me know if you have a better idea
_The documentation is not available anymore as the PR was closed or merged._