www/py-django-recaptcha: Update to 3.0.0

• Switch back to PyPI because the sdist is available there again.

• Update WWW field as the upstream repository got a new maintainer and make the pkg-descr a bit more detailed.

Changelog:

https://github.com/torchbox/django-recaptcha/releases/tag/3.0.0

Approved by: myself (python, maintainer)