Update nixpkgs

[github-actions]

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

Flake lock file updates:

• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/698fd43e541a6b8685ed408aaf7a63561018f9f8?narHash=sha256-/VyiyGD2q6qN/uAvotKxXuQJWLlmSckAdf7S8jj4Q5c%3D' (2024-04-27)
  → 'github:NixOS/nixpkgs/2b1f64b358f2cab62617f26b3870fd0ee375d848?narHash=sha256-9P2M0%2Btf1TE7Z5PwDVwhheuD2mFf6/phPr0Jvl7cxcc%3D' (2024-04-27)

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, run:

git branch -D update_flake_lock_action
git fetch origin
git checkout update_flake_lock_action
git commit --amend --no-edit
git push origin update_flake_lock_action --force