chore(nix): bump rust-overlay from 25d75be to 0206130 (#11)

Bumps [rust-overlay](https://github.com/oxalica/rust-overlay) from `25d75be` to `0206130`.
- [Commits](oxalica/rust-overlay@25d75be...0206130)

---
updated-dependencies:
- dependency-name: rust-overlay
  dependency-version: 02061303f7c4c964f7b4584dabd9e985b4cd442b
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]