flake.lock: Update (#569)

Flake lock file updates:

• Updated input 'flake-utils':
    'github:numtide/flake-utils/bee6a7250dd1b01844a2de7e02e4df7d8a0a206c' (2022-06-24)
  → 'github:numtide/flake-utils/7e2a3b3dfd9af950a856d66b0a7d01e3c18aa249' (2022-07-04)
• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/0ea7a8f1b939d74e5df8af9a8f7342097cdf69eb' (2022-07-02)
  → 'github:NixOS/nixpkgs/4a01ca36d6bfc133bc617e661916a81327c9bbc8' (2022-07-14)
• Updated input 'rust-overlay':
    'github:oxalica/rust-overlay/be0b8a7cbf95d43f23ef0bfa781d644a43c75396' (2022-07-02)
  → 'github:oxalica/rust-overlay/2cd36d4aef875867ee1d7963541ccb3ae50b358c' (2022-07-16)

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>