flake.lock: Update Nixpkgs

This fixes evaluation for Windows. There are unfortunately deps that
still don't build, but this can be fixed next.

Flake lock file updates:

• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/52faf482a3889b7619003c0daec593a1912fddc1?narHash=sha256-6hl6L/tRnwubHcA4pfUUtk542wn2Om%2BD4UnDhlDW9BE%3D' (2025-03-30)
  → 'github:NixOS/nixpkgs/f675531bc7e6657c10a18b565cfebd8aa9e24c14?narHash=sha256-gbl9hE39nQRpZaLjhWKmEu5ejtQsgI5TWYrIVVJn30U%3D' (2025-04-09)

Author: Ericson2314