CI improvements

[cdce8p]

Description

Similar changes to pylint-dev/pylint#7651

• Remove restore-keys. Especially on Windows there are issues with reusing old cache entries and trying to install newer versions. Those are just skipped if the old one still satisfies the requirement. It's easy / fast enough to create a whole new environment if something changes.
• Add check-latest: true for setup-python action. This will prevent cache restore issue when runners use different Python patch versions. https://github.com/actions/setup-python/blob/main/docs/advanced-usage.md#check-latest-version
• Add KEY_PREFIX env variable to more easily identify the key prefix in each workflow.
• Replace setup.cfg with pyproject.toml for file hash

[coveralls]

Pull Request Test Coverage Report for Build 3378006405

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 92.272%

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Totals
Change from base Build 3367353146:	0.0%
Covered Lines:	9862
Relevant Lines:	10688

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💛 - Coveralls

[Pierre-Sassoulas]

I'm going to trust you on this one, I'm not an expert. The new hash key does make much more sense than manually upgrading the cache indeed. I wonder why I did not think of this when upgrading astroid in pylint,

[cdce8p]

The new hash key does make much more sense than manually upgrading the cache indeed. I wonder why I did not think of this when upgrading astroid in pylint,

You might want to take a look at pylint-dev/pylint#7651 then. It does simplify update astroid in pylint. The primer test failure there is expected.