Catch cache.restoreCache errors and warn instead of fail

[maurobringolf]

I did this to mitigate https://github.com/actions/cache/issues/820. Probably a bit blunt to treat all Errors the same which is why I marked this as a draft and am open to suggestions.

[smorimoto]

If the cache restore fails, the workflow may proceed without initializing some components that should be initialized, which is one of the workarounds that currently has not been fully implemented. So even if this is merged, it will fail if there is a problem with the cache server.