Have a way to pin pip versions

[twz123]

Description:
Pip is currently always updated to the latest version. This happens somewhere in the setup scripts in actions/python-versions. As far as I can tell, there's no way to skip that, or even better, pin pip to a specific version. Albeit one can downgrade pip again in a subsequent step, this seems like something to have as a proper feature: It would be cool if there's some means of doing this, e.g. via a new optional input parameter, or an OS environment variable.

Justification:
The recent pip 22.3 update from 2022-10-15 broke some builds. A manual downgrade to pip 22.2.2 solved it. Upgrading pip via separate PRs seems desirable for some folks (e.g. for me 🙂).

Are you willing to submit a PR?
Yes.

[dmitry-shibanov]

Hello @twz123. Thank you for your feature request. We'll investigate it.