flake.lock: Update (ggerganov#6266)

Flake lock file updates:

• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/d691274a972b3165335d261cc4671335f5c67de9' (2024-03-14)
  → 'github:NixOS/nixpkgs/44d0940ea560dee511026a53f0e2e2cde489b4d4' (2024-03-23)

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