Remove support for Python 3.7 (and define plans for Python 3.8 and 3.9)

[PhilippWendler]

As discussed previously we will remove support for Python 3.7 in one of the next releases. I suspect this will not be critical because all currently supported versions of Ubuntu or Debian ship Python 3.8 or newer. We should still wait for at least one more release and announce the upcoming change in the changelog.

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As a heads-up, we plan to remove support for Python 3.8 once Ubuntu 20.04 goes out of support, i.e., in April 2025. At that point we might even drop support for Python 3.9 and jump directly to requiring Python 3.10.

Please comment here if either of these plans are problematic for you.

[leventeBajczi]

I'm still using Python 3.6 via the SLURM extension to Benchexec (#995), on the Komondor cluster in Hungary. Komondor by default has Python 3.6.8 installed. Because right now benchexec works for me using this python version, I don't want it to break -- I do understand that other parts of Benchexec may already rely on later versions, and also that this could be modified any time, but right now, it still works just fine. However, should Benchexec move away from supporting (even unofficially) this version, the worst that could happen for me is that I would need a local copy of a newer python version, which I don't think is that hard to achieve - however, I admit I have not yet tried to go down that route. So I don't want to be the one holding back benchexec with my (admittedly very niche) use-case.

[PhilippWendler]

Thanks for the feedback. Then we will follow the current plan.

[YashGaur000]

I think let it be as it is for now. Benchexe should remove support for Python 3.8 once Ubuntu 20.04 goes out of support, in 2025. And jumping directly to 3.10 version of python will be a great decision.