flake: update inputs

[github-actions]

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

Flake lock file updates:

• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/eabe8d3eface69f5bb16c18f8662a702f50c20d5' (2024-01-09)
  → 'github:NixOS/nixpkgs/5f5210aa20e343b7e35f40c033000db0ef80d7b9' (2024-01-22)

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

[lilyinstarlight]

Needs NixOS/nixpkgs#282468 before the build for the flake bump will work