Documented save-if: ${{ github.ref == 'refs/head/master' }} does not work.

[rukai]

After reading the readme, I added save-if: ${{ github.ref == 'refs/head/main' }} (we use main instead of master) to my workflow in order to only cache from the main branch.
However now the workflow is never cached regardless of if it is running on the main branch or on a PR.
Here is an example run on the main branch: https://github.com/shotover/shotover-proxy/actions/runs/5958570260/job/16162971043
It fetches an old cache from before I added the save-if but then in the post-run it doesnt write to the cache.

So it appears the documentation is wrong or the feature is broken.

[rukai]

I found the documentation for github.ref
It says the syntax is refs/heads/<branch_name> instead of refs/head/<branch_name>!
I'll make a PR to fix it.