textproc/py-pdfminer.six: Update to 20211012

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

• Remove the test suite as it makes only sense for upstream testing in its current condition and therefore isn't supplied with the sdist.

• Update pkg-descr to match reality.

Changelog:

https://github.com/pdfminer/pdfminer.six/blob/develop/CHANGELOG.md#20211012

PR: 262101
Reported by: rsmith@xs4all.nl