chore(nix): bump rust-overlay from 40e6ccc to 2d35c43 (#16)

Bumps [rust-overlay](https://github.com/oxalica/rust-overlay) from `40e6ccc` to `2d35c43`.
- [Commits](oxalica/rust-overlay@40e6ccc...2d35c43)

---
updated-dependencies:
- dependency-name: rust-overlay
  dependency-version: 2d35c4358d7de3a0e606a6e8b27925d981c01cc3
  dependency-type: direct:production
...

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