Use Swatinem/rust-cache instead of actions/cache

[zanieb]

I think this is a bit better practice. The cache handling in this action is relatively robust.

[reneleonhardt]

@charliermarsh Approved but not merged, are there any problems?

[zanieb]

It's just not a critical change, why do you ask..?

[reneleonhardt]

It has been approved 8 months ago, makes you wonder why not just merge it since then... now it has conflicts.

[indygreg]

The Rust cache has marginal improvements to CI times. We can likely improve cache hit times by modifying actions/cache.

Given the criticality of PBS to the larger software ecosystem and that popularity making it an attractive target for software supply chain attacks, I have a soft preference for avoiding 3rd party GitHub Actions. If we do adopt 3rd party actions, I think we should pin the Git commit SHA so the implementation can't be changed out from under us without an explicit Git commit to this project.

[zanieb]

Agreed, astral-sh/uv#12189 has been working well for us.