Add hermes commit to github action cache (#43067)

Summary:
The test_ios_rntester-Hermes which runs in github actions was created to make sure that recent commits on Hermes/main won't be breaking React Native
However, we discovered that the job was using a cached version of hermes and it was't really downloading the latest hermes every time.

With this change, the cocoapods cache will be invalidated whenever there is a commit on hermes/main, forcing the job to reinstall the dependencies when that happens.

bypass-github-export-checks

## Changelog:
[internal] - Fixed GH Action job to properly refetch newest version on Hermes when it changes.

Pull Request resolved: https://github.com/facebook/react-native/pull/43067

Test Plan:
Github Actions must be green and the action should show that a new version of Hermes is downloaded.

The commit is downloaded here:
 {F1457505882}

And it is used here, notice the last hash:
 {F1457505989}

Reviewed By: motiz88

Differential Revision: D53853963

Pulled By: cipolleschi

fbshipit-source-id: 7a65dd72a21b6da12b826273d1c92bb90b678652