Addition in lintian to warn about debian/pyversions file

[Joseph Herlant <herlantj@gmail.com>]

Hi guys,

FYI I am requesting a new lintian tag to warn about the presence of
the debian/pyversions file as it is supposed to be obsolete since
dh_python2 [1].

According to the policy[2], we are supposed to use the
X-Python3-Version field in debian/control to specify the version now.

Please let me know if that is an issue for you.

Bug report: #898592

Thanks,
Joseph

[1] https://wiki.debian.org/Python/TransitionToDHPython2
[2] https://www.debian.org/doc/packaging-manuals/python-policy/ch-module_packages.html#s-specifying_versions