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=650e572363c091045cdbc5b36b0f4c1f614d3058&shallow=1' (2025-07-12)
• 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=be9e214982e20b8310878ac2baa063a961c1bdf6&shallow=1' (2025-07-09)

Author: github-actions[bot]