Support github cache

[DiamonDinoia]

Dear @aminya,

Thank you for providing this action. It is really helpful to me.

I would like to ask if there is any technical reason why github cache cannot be leveraged somehow to avoid re-installing the same packages every time. My pipelines run the same env for multiple jobs and sometimes setup-cpp is the step that takes most of the time (example: https://github.com/DiamonDinoia/finufft/actions/runs/13046204138/job/36416878122). Is it possible to cache the installations, or the resulting image entirely to avoid doing the same work all the time?

Thanks,
Marco

edit: if you can help me setting up custom docker images. I am happy to contribute to the documentation