[PM-1919] PEP 668 / non-os Python dependencies

[mayani]

The Pegasus build currently depends on extra packages/versions which are not shipped by the OS vendor. For our binary packages, we have solved the problem in our buildenv Docker containers by upgrading some things via pip. For example:

RUN pip3 install --break-system-packages --upgrade pip setuptools==45.3.0 tox

This is no longer allowed:

https://peps.python.org/pep-0668/

The second problem with this approach is that we can not express these dependencies in rpm/deb packaging, and thus our packages are not buildable outside our own environment.

One possible solution is a temporary venv which is setup as part of the build process. I don't know if this will solve the Debian pbuilder problem (might not allow downloads like that during the build process), but it would certainly make it so Pegasus could be built easily by users.

Reporter: @rynge
Watchers:
@rynge