dns/py-adns: update to 1.6.0 and take maintainership

While here:

• Added DIST_SUBDIR The PyPI source archive for the Python module (adns-1.6.0.tar.gz) has the same filename as the C library dns/adns distfile.
• Removed post-patch as this is no longer needed
• Added post-install to strip .so file (fixes stage-qa warning)

Changelog: https://github.com/trolldbois/python3-adns/compare/v1.4-py1...1.6.0

PR: 288666
Reported by: Atanu Biswas <atanubiswas484@gmail.com> (new maintainer)