flake.lock: Update

Flake lock file updates:

• Updated input 'fenix':
    'github:nix-community/fenix/6643d56d9a78afa157b577862c220298c09b891d?narHash=sha256-vmbu97JXqr9/sTWR5XRh646jkp8a0J9m0o6JIQTdjE4%3D' (2025-06-28)
  → 'github:nix-community/fenix/e91719882d0e4366202cc9058eb21df74c0bdb92?narHash=sha256-rSw0b/ahoZebcp%2BAZG7uoScB5Q59TYEE5Kx8k0pZp9E%3D' (2025-07-19)
• Updated input 'fenix/rust-analyzer-src':
    'github:rust-lang/rust-analyzer/317542c1e4a3ec3467d21d1c25f6a43b80d83e7d?narHash=sha256-hMNZXMtlhfjQdu1F4Fa/UFiMoXdZag4cider2R9a648%3D' (2025-06-25)
  → 'github:rust-lang/rust-analyzer/330c4ed11c4e1eef0999a2cd629703a601da1436?narHash=sha256-YnG3d44oX%2Bg2ooUsNWT%2BIi24w6T%2Bb0dj86k0HkIFUj4%3D' (2025-07-18)
• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/80d50fc87924c2a0d346372d242c27973cf8cdbf?narHash=sha256-3u6rEbIX9CN/5A5/mc3u0wIO1geZ0EhjvPBXmRDHqWM%3D' (2025-06-27)
  → 'github:NixOS/nixpkgs/6b4955211758ba47fac850c040a27f23b9b4008f?narHash=sha256-dPALCtmik9Wr14MGqVXm%2BOQcv7vhPBXcWNIOThGnB/Q%3D' (2025-07-19)

Author: github-actions[bot]