create new cache key on each run when saving previous commit hash

[haileyok]

So, it turns out that actions/checkout@v4 does not overwrite cache keys. This was revealed after fixing a boolean check last night. Now, TestFlight releases are using a bad previous commit hash which is always triggering a new build now.

Instead, let's save to a new key on every run. We'll pull from the cache using the last-successful-deployment-commit-{branch}- prefix to find the old one instead of just a static string.

Production builds were running appropriately because they do not pull from the cache but rather use version-specific tag for a base commit, so this only affects internal builds.

This also lets us actually use the cancel-in-progress correctly, since the cache will actually be properly updated.

[render]

Your Render PR Server URL is https://social-app-pr-3898.onrender.com.

Follow its progress at https://dashboard.render.com/web/srv-cot8avmn7f5s73cvteag.

[github-actions]

Old size	New size	Diff
6.88 MB	6.88 MB	0 B (0.00%)

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