[mythtv] Ad ticket #13567: Revise dependencies for packaging

[Roland Ernst]

I'd really like to have MythTV v31 for Debian/Ubuntu released
without dependencies to python2.

Current situation:
The deb packages produced by 'ppa:mythbuntu/31' have dependencies
to python2 but do not install the MythTV Python Bindings for
python2, only for python3. Therefore, users do not have a working
solution for the MythTV Python Bindings with python2 out of the box.

Since the release notes for MythTV v31 at
https://www.mythtv.org/wiki/Release_Notes_-_31
marked python2 support as deprecated, is it enough to
provide a user-script that installs the Python Bindings for
python2 based on the already installed version for python3?

This script could be placed on the wiki and linked from the
official release notes with a notification, like
"Debian/Ubuntu users still requiring python2 support need to
follow instructions on..."

This script will extract the installed Python3 Bindings and
install it via "setup.py" for python2, either globally, or locally
for the current user. Even a "python virtual environment" setup
is possible in this case.

I can provide this script, if agreed.

Regards,
Roland