Save cache even if failures

[IanButterworth]

I think it makes sense to cache the depot even if there have been test failures.

Unfortunately it requires an upstream change https://github.com/actions/cache/pull/1242

[omus]

Alternatively, if we're willing to switch away from using a composite action we can use runs.post to perform the cache save (unfortunately, this is basically re-implementing actions/cache). It's rather unfortunate composite actions don't support the pre/post steps.

[IanButterworth]

https://github.com/actions/cache/pull/1242 has been merged and should be out in the next release

[omus]

It's out in the v4 release: https://github.com/actions/cache#v4

[IanButterworth]

Great. I don't immediately see why it warranted a major release..