Remove the caching from the CI workflow
I don't trust it. Compare these two runs: 1. https://github.com/input-output-hk/cardano-haskell-packages/actions/runs/4532746158/jobs/7984714895 2. https://github.com/input-output-hk/cardano-haskell-packages/actions/runs/4516172089/jobs/7954255360 The second is on the parent commit of the first, the commit itself is a no-op, and yet the derivations they build are not the same! Doing the same locally, I get a) a different derivation, but b) the same derivation for both. I conclude that what the CI is doing is questionable, the cache seems like the most likely source of pollution. I suspect whatever is causing this was also responsible for the no-op PR spending a lot of time building tons of stuff.
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