chore(deps): update flake.lock

[github-actions]

Automated changes by the update-flake-lock GitHub Action.

Flake lock file updates:

• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/d1c15b7' (2026-02-16)
  → 'github:NixOS/nixpkgs/c0f3d81' (2026-02-27)
• Updated input 'rust-overlay':
    'github:oxalica/rust-overlay/8507836' (2026-02-21)
  → 'github:oxalica/rust-overlay/a1ab5e8' (2026-02-28)

Running GitHub Actions on this PR

GitHub Actions will not run workflows on pull requests which are opened by a GitHub Action.

To run GitHub Actions workflows on this PR, close and re-open this pull request.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}