flake.lock: Update (#865)

Flake lock file updates:

• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/d3c42f187194c26d9f0309a8ecc469d6c878ce33?narHash=sha256-cHar1vqHOOyC7f1%2BtVycPoWTfKIaqkoe1Q6TnKzuti4%3D' (2024-12-17)
  → 'github:NixOS/nixpkgs/634fd46801442d760e09493a794c4f15db2d0cbb?narHash=sha256-NYVcA06%2BblsLG6wpAbSPTCyLvxD/92Hy4vlY9WxFI1M%3D' (2024-12-27)
• Updated input 'rust-overlay':
    'github:oxalica/rust-overlay/f9086701f5f3d36b8e5f4a3b9c93579ebc2581e6?narHash=sha256-0DUuObdcPITVOMMymq2y6YlM%2B%2BQEWXZO3cTm6RGYgL8%3D' (2024-12-21)
  → 'github:oxalica/rust-overlay/a16b9a7cac7f4d39a84234d62e91890370c57d76?narHash=sha256-3zXufMRWUdwmp8/BTmxVW/k4MyqsPjLnnt/IlQyZvhc%3D' (2024-12-28)

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