flake.lock: Update

Flake lock file updates:

• Updated input 'nixpkgs':
    'git+https://github.com/NixOS/nixpkgs?ref=nixos-unstable-small&rev=a1ba3c5c21b2424ad0bd13bbbfa50ebfbd54823e&shallow=1' (2025-06-04)
  → 'git+https://github.com/NixOS/nixpkgs?ref=nixos-unstable-small&rev=ebd3748a6b97de45844aa62701b81df35c5c1269&shallow=1' (2025-06-06)
• Updated input 'treefmt-nix':
    'github:numtide/treefmt-nix/1f3f7b784643d488ba4bf315638b2b0a4c5fb007?narHash=sha256-9YzfeN8CB6SzNPyPm2XjRRqSixDopTapaRsnTpXUEY8%3D' (2025-05-26)
  → 'github:numtide/treefmt-nix/a05be418a1af1198ca0f63facb13c985db4cb3c5?narHash=sha256-eEy8cuS0mZ2j/r/FE0/LYBSBcIs/MKOIVakwHVuqTfk%3D' (2025-06-06)

Author: github-actions[bot]