update Nix flake inputs

Flake lock file updates:

• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/c31898adf5a8ed202ce5bea9f347b1c6871f32d1?narHash=sha256-yumd4fBc/hi8a9QgA9IT8vlQuLZ2oqhkJXHPKxH/tRw%3D' (2024-10-06)
  → 'github:NixOS/nixpkgs/2768c7d042a37de65bb1b5b3268fc987e534c49d?narHash=sha256-AlcmCXJZPIlO5dmFzV3V2XF6x/OpNWUV8Y/FMPGd8Z4%3D' (2024-10-23)
• Updated input 'rust-overlay':
    'github:oxalica/rust-overlay/d216ade5a0091ce60076bf1f8bc816433a1fc5da?narHash=sha256-r%2BSa1NRRT7LXKzCaVaq75l1GdZcegODtF06uaxVVVbI%3D' (2024-10-08)
  → 'github:oxalica/rust-overlay/29b1275740d9283467b8117499ec8cbb35250584?narHash=sha256-Rb6JUop7NRklg0uzcre%2BA%2BEbrn/ZiQPkm4QdKg6/3pw%3D' (2024-10-24)
• Updated input 'rust-overlay/nixpkgs':
    'github:NixOS/nixpkgs/e6cea36f83499eb4e9cd184c8a8e823296b50ad5?narHash=sha256-WdWDpNaq6u1IPtxtYHHWpl5BmabtpmLnMAx0RdJ/vo8%3D' (2024-06-15)
  → 'github:NixOS/nixpkgs/b69de56fac8c2b6f8fd27f2eca01dcda8e0a4221?narHash=sha256-f0SBJz1eZ2yOuKUr5CA9BHULGXVSn6miBuUWdTyhUhU%3D' (2024-10-10)