flake.lock: Update

[yannham]

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

Flake lock file updates:

• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/5690c4271f2998c304a45c91a0aeb8fb69feaea7' (2023-08-25)
  → 'github:NixOS/nixpkgs/aa8aa7e2ea35ce655297e8322dc82bf77a31d04b' (2023-09-01)

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