chore(ci): track dependencies updates to add them to Nix cache

[ch4og]

Description of change

Now it will add Cargo.toml, Cargo.lock, flake.lock hashes to cache name so if dependency updates in these files it will know that new cache should be saved.

Also since much more caches will be created cause of this it adds auto purge of old unused caches (only Nix ones)

Please let me know if I missed any other files where dependencies can come from

It won't affect build time since when dependency version changes it'll use old partial cache

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 3.31%. Comparing base (03de375) to head (f17e7d0). Report is 1 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #84 +/- ## ===================================== Coverage 3.31% 3.31% ===================================== Files 19 19 Lines 2417 2417 ===================================== Hits 80 80 Misses 2337 2337 ```

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