Benchmark runner script

[trexfeathers]

🚀 Pull Request

Description

Moves benchmark convenience scripts from noxfile.py into a dedicated bm_runner.py.

• Better suited to providing user help information.
• Runner only uses built-in dependencies.
• Agnostic to Nox/Tox/some-other-future-architecture.

Needed before #5184 can be completed.

This also introduces a low-overhead way of keeping the listed Python versions aligned in the various files - see test_coding_standards.test_python_versions().

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Consult Iris pull request check list

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (512ca75) 89.27% compared to head (d2c8c79) 89.27%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5215   +/-   ##
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  Coverage   89.27%   89.27%           
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  Files          88       88           
  Lines       22258    22258           
  Branches     4867     4867           
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  Hits        19871    19871           
  Misses       1641     1641           
  Partials      746      746           

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[lbdreyer]

This is looking good I just have a few, hopefully minor, comments.

Regarding the new test_python_versions in test_coding_standards.py, I can see the benefit of it as we will no doubt trip ourselves up over this in future. I have some reservations about the implementation as it is very dependent on the formating of the specified files, but I assume we won't be modifying those files that often, so it shouldn't be such a regular issue. In an ideal world we would have one location we keep the supported python versions and then all these specialised config files would refer to that, but that is likely very complex (or impossible) to implement. So I'm happy to go with what we have right now, and then we can always change it in future

[trexfeathers]

Thanks @lbdreyer!