This action makes sure to always have the correct GHC and/or stack
version installed in all environments. This solves problem where ghc or
stack might not be available on newer macos images anymore or where
ghcup is not available by default on our new custom github runner on
arm.
This is a first step to split up the cabal and stack caches in separate
pieces. Here we split the work folder, which just contains the
postgrest-specific build artifacts, into a separate cache.
More fine-grained caching should give us better cache hits and much
fewer upload size in the regular case, improving CI performance.
Since the work file caches are very small (about 30-40 MB) they are
cached for PRs, too. This will allow the majority of PRs, which only
change source code files, but no dependencies, to still have cached
their build files for additional commits.
This restores caches on all branches and pull requests, but only stores
them on the main branch and release branches. This prevents those caches
from being evicted early when we hit the 10 GB limit quickly.
Using the -latest tag is potentially prone to errors, because an update of the tag
could break our CI. This recently happend with macos-latest, which we downgraded
to macos-12 earlier.
Using an explicit version reference makes this problem much less likely - in fact
renovate will pick up new versions once they exist and will suggest updates for it.
Thus, we will see the failures in a related PR instead of randomly everywhere.
This is to reduce storage requirements for GitHub Actions cache. We already build with GHC 9.4.x
via Nix on Linux x64, via stack on FreeBSD, MacOS and Windows and via Cabal on Linux ARM. That
should cover 9.4.x enough.
