nix: update flake.lock (ggerganov#5969)

Flake lock file updates:

• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/1536926ef5621b09bba54035ae2bb6d806d72ac8' (2024-02-29)
  → 'github:NixOS/nixpkgs/9df3e30ce24fd28c7b3e2de0d986769db5d6225d' (2024-03-06)

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