chore: update flake.lock

[mrcjkb]

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

Flake lock file updates:

• Updated input 'nixpkgs':
    'github:nixos/nixpkgs/46ed466081b9cad1125b11f11a2af5cc40b942c7' (2023-07-15)
  → 'github:nixos/nixpkgs/29bcead8405cfe4c00085843eb372cc43837bb9d' (2023-07-15)

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