chore(example): Update flake.lock

Flake lock file updates:

• Updated input 'haskell-flake':
    'github:srid/haskell-flake/af2ba40f23824556b12d1cdfdf392e263876d644?narHash=sha256-gV/B1PWOwpLjy2OCHMS/fJ8GItMRoflW/g3kXB8/skg%3D' (2025-06-05)
  → 'github:srid/haskell-flake/39065472d2587af93a502423276bfb98c2c6fb09?narHash=sha256-Yif99ho8GNgXP0l9vxPHCKi7X16Cf7rwVd%2BHW1cMVeQ%3D' (2025-07-14)
• Updated input 'nixpkgs':
    'github:nixos/nixpkgs/2a2130494ad647f953593c4e84ea4df839fbd68c?narHash=sha256-Q82Ms%2BFQmgOBkdoSVm%2BFBpuFoeUAffNerR5yVV7SgT8%3D' (2025-07-08)
  → 'github:nixos/nixpkgs/6b4955211758ba47fac850c040a27f23b9b4008f?narHash=sha256-dPALCtmik9Wr14MGqVXm%2BOQcv7vhPBXcWNIOThGnB/Q%3D' (2025-07-19)

Author: github-actions[bot]