Automate check for consistent upstream dependencies

[jakob-keller]

          By the way, you should be able to write a simple check built into the pre-commit framework, verifying that these values are the same. Here's an example of embedding a few lines of python there: https://github.com/sphinx-contrib/sphinxcontrib-towncrier/blob/648f815/.pre-commit-config.yaml#L45-L74.

Originally posted by @webknjaz in #1246 (comment)

[webknjaz]

Or are you suggesting to merely check that those three lines are always touched at the same time?

Yes, this.

[thehesiod]

aha, looks like we can use this:

>>> from importlib.metadata import requires
>>> requires('botocore')
['jmespath (<2.0.0,>=0.7.1)', 'python-dateutil (<3.0.0,>=2.1)', 'urllib3 (<1.27,>=1.25.4) ; python_version < "3.10"', 'urllib3 (!=2.2.0,<3,>=1.25.4) ; python_version >= "3.10"', "awscrt (==0.23.4) ; extra == 'crt'"]

there's an undoc'd way to parse that: from pip._internal.req.constructors import install_req_from_line, probably a better way as well

[thehesiod]

eh since it's just a unittest should be find using the function, if it breaks, we update it