Description:

A cache key looks like this setup-python-Linux-python-3.11.0-beta.3-pip-60d374041db12689c3d346e149aa43744f06aa781ab1c8cbbe70e0b09b98dd70.
It is specific to a Python version and OS type. It has to be specific to a version of an operating system too.

Justification:

PyPI provides source distributions of packages (archives with code) and built distributions (wheels). When a wheel suitable for an environment is not found on PyPI, a source distribution is usually downloaded and a wheel is built locally. The source may contain some code that needs to be compiled (C, Rust, etc.)

On Linux, a compiled wheel may depend on a specific version of a shared library. Different Ubuntu releases used on GitHub Actions may provide different versions of shared libraries. Therefore, a wheel compiled on Ubuntu 20.04 may be incompatible with Ubuntu 22.04. This makes the cache feature unusable when a workflow runs jobs on multiple Ubuntu versions or when an Ubuntu version is changed in a workflow.

https://github.com/urllib3/urllib3/runs/6817232938 is an example of a failed run.
The error is caused by a cffi wheel that was compiled and cached in Ubuntu 20.04 previously where it depended on libffi.so.7.
Ubuntu 22.04 (that provides libffi.so.8) restored that cache archive because it composed the same cache key, and cffi become unusable there (urllib3/urllib3#2626 (comment) provides a little bit more info.)

BTW, #188 may be a related bug report issue.

Are you willing to submit a PR?

No. Although, I guess it is a matter of changing the following lines of code to include a version of an OS in the key.