flake.lock: Update

Flake lock file updates:

• Updated input 'flake-parts':
    'github:hercules-ci/flake-parts/4524271976b625a4a605beefd893f270620fd751?narHash=sha256-%2BuWLQZccFHwqpGqr2Yt5VsW/PbeJVTn9Dk6SHWhNRPw%3D' (2025-09-01)
  → 'github:hercules-ci/flake-parts/0678d8986be1661af6bb555f3489f2fdfc31f6ff?narHash=sha256-qIoWPDs%2B0/8JecyYgE3gpKQxW/4bLW/gp45vow9ioCQ%3D' (2026-05-05)
• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/8eb28adfa3dc4de28e792e3bf49fcf9007ca8ac9?narHash=sha256-NOrUtIhTkIIumj1E/Rsv1J37Yi3xGStISEo8tZm3KW4%3D' (2025-09-05)
  → 'github:NixOS/nixpkgs/549bd84d6279f9852cae6225e372cc67fb91a4c1?narHash=sha256-hGdgeU2Nk87RAuZyYjyDjFL6LK7dAZN5RE9%2BhrDTkDU%3D' (2026-05-05)
• Updated input 'treefmt-nix':
    'github:numtide/treefmt-nix/5eda4ee8121f97b218f7cc73f5172098d458f1d1?narHash=sha256-ySNJ008muQAds2JemiyrWYbwbG%2BV7S5wg3ZVKGHSFu8%3D' (2025-09-24)
  → 'github:numtide/treefmt-nix/790751ff7fd3801feeaf96d7dc416a8d581265ba?narHash=sha256-pc20NRoMdiar8oPQceQT47UUZMBTiMdUuWrYu2obUP0%3D' (2026-04-08)

Author: github-actions[bot]