flake.lock: Update

Flake lock file updates:

• Updated input 'nixos-stable':
    'git+https://github.com/NixOS/nixpkgs?ref=nixos-25.05&rev=70c74b02eac46f4e4aa071e45a6189ce0f6d9265&shallow=1' (2025-06-06)
  → 'git+https://github.com/NixOS/nixpkgs?ref=nixos-25.05&rev=c58bc7f5459328e4afac201c5c4feb7c818d604b&shallow=1' (2025-11-20)
• Updated input 'nixos-unstable':
    'git+https://github.com/NixOS/nixpkgs?ref=nixpkgs-unstable&rev=08fcb0dcb59df0344652b38ea6326a2d8271baff&shallow=1' (2025-06-08)
  → 'git+https://github.com/NixOS/nixpkgs?ref=nixpkgs-unstable&rev=878e468e02bfabeda08c79250f7ad583037f2227&shallow=1' (2025-11-22)

Author: github-actions[bot]