flake.lock: Update

[github-actions]

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

Flake lock file updates:

• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/1807c2b91223227ad5599d7067a61665c52d1295?narHash=sha256-Pzyb%2BYNG5u3zP79zoi8HXYMs15Q5dfjDgwCdUI5B0nY%3D' (2024-12-22)
  → 'github:NixOS/nixpkgs/9c6b49aeac36e2ed73a8c472f1546f6d9cf1addc?narHash=sha256-i/UJ5I7HoqmFMwZEH6vAvBxOrjjOJNU739lnZnhUln8%3D' (2025-01-14)

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