Python-Setup: run auto_install_packages.py with -B flag

[aibaars]

This avoids creating a pycache folder in the _actions folder, which
may cause file ownership problems on self-hosted runners
when run in a docker container.

Merge / deployment checklist

• Confirm this change is backwards compatible with existing workflows.
• Confirm the readme has been updated if necessary.
• Confirm the changelog has been updated if necessary.

[aeisenberg]

Is there any performance improvements to creating a pycache folder? We could use the -X pycache_prefix=PATH option instead to place them in the runner temp folder.

[aeisenberg]

Ah...I see you already went over that in the internal issue. That option only exists in 3.8 or later. If there is likely to be noticeable speedup when using the pycache, then we can first detect which python version we are using and only use the option for 3.8 or later.

I suspect that this is not the case, though and what you have is fine.

[RasmusWL]

out of curiosity, why did you choose to revert the PYTHONDONTWRITEBYTECODE=1 version of this fix?

[aibaars]

out of curiosity, why did you choose to revert the PYTHONDONTWRITEBYTECODE=1 version of this fix?

I meant to mention that approach in the PR and ask whether it would be preferred or not. The drawback of setting the environment variable is that it affects all python invocations, not just the problematic one running the script in the setup-python action. I doubt it would cause any problems, but who knows.