flake.lock: Update (#1922)

Flake lock file updates:

• Updated input 'nixpkgs':
    'github:nixos/nixpkgs/09906cab24f49dedbb5b429f8b6c840d4e75b1b7?narHash=sha256-YKdbjp8rb4BH6hq1r7/IcJ12XvB5tsZW76sDb9G/eII%3D' (2025-08-17)
  → 'github:nixos/nixpkgs/73347dcecffada777f109886943fd3218266dde5?narHash=sha256-CA26lQJM1wM2//0ThWcp2ZeRqgcLfk892lEKRkypNbI%3D' (2025-08-23)

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: github-actions[bot]