build,python: Fix make distcheck for Python 3.9+

* lang/python/Makefile.am (uninstall-local): Remove installed .egg
folders.

Python 3.9+ install the module into a gpg-*.egg folder instead of in
"gpg" with accompanying gpg-*.egg-info file. Moreover, Python 3.9+
normalize version numbers, e.g. the version 1.24.0_beta576 is normalized
as 1.24.0b576.