Add update-lock.py script to compile requirements using pip-tools

[tobiasdiez]

We add a litle wrapper around pip-compile that transforms the abstract version constraints of #37446 into pinned version specifications in requirement.txt files (see #37461 for the result).

The PR #37446 is sadly on the pile of PRs disputed by Matthias, so I'll not add it as an explicit dependency. The script can be tested with python tools/update-lock.py src (after pip install pip-tools) although it then does not generate the test/doc/linter-requirment.txt files of #37461.

📝 Checklist

• The title is concise, informative, and self-explanatory.
• The description explains in detail what this PR is about.
• I have linked a relevant issue or discussion.
• I have created tests covering the changes.
• I have updated the documentation accordingly.

⌛ Dependencies

[github-actions]

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[mkoeppe]

@roed314 @jhpalmieri I set "disputed" here because when the PR was opened, I was not able to comment because Tobias had blocked me without explanation or giving notice to the sage-abuse committee. It appears that now I can comment, so I am removing "disputed".
There has not been any review yet here, so conducting a vote would seem premature.

[tobiasdiez]

This is now included in #37461.