chore(nix): bump rust-overlay from bc83d66 to 4852a8a

Bumps [rust-overlay](https://github.com/oxalica/rust-overlay) from `bc83d66` to `4852a8a`.
- [Commits](oxalica/rust-overlay@bc83d66...4852a8a)

---
updated-dependencies:
- dependency-name: rust-overlay
  dependency-version: 4852a8aa041c94af55e136cde5b8b6d42c3563e8
  dependency-type: direct:production
...

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