flake.lock: Update (#1930)

Automated changes by the
[update-flake-lock](https://github.com/DeterminateSystems/update-flake-lock)
GitHub Action.

```
Flake lock file updates:

• Updated input 'git-hooks-nix':
    'github:cachix/git-hooks.nix/b68b780b69702a090c8bb1b973bab13756cc7a27?narHash=sha256-t3T/xm8zstHRLx%2BpIHxVpQTiySbKqcQbK%2Br%2B01XVKc0%3D' (2025-12-16)
  → 'github:cachix/git-hooks.nix/f0927703b7b1c8d97511c4116eb9b4ec6645a0fa?narHash=sha256-6MkqajPICgugsuZ92OMoQcgSHnD6sJHwk8AxvMcIgTE%3D' (2026-01-01)
• Updated input 'git-hooks-nix/flake-compat':
    'github:edolstra/flake-compat/f387cd2afec9419c8ee37694406ca490c3f34ee5?narHash=sha256-XKUZz9zewJNUj46b4AJdiRZJAvSZ0Dqj2BNfXvFlJC4%3D' (2025-10-27)
  → 'github:NixOS/flake-compat/5edf11c44bc78a0d334f6334cdaf7d60d732daab?narHash=sha256-vNpUSpF5Nuw8xvDLj2KCwwksIbjua2LZCqhV1LNRDns%3D' (2025-12-29)
• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/deefe7fae28c478ef2b0e0f72352233806fc6da2?narHash=sha256-cTpRd20EknSDkfpumLXIlO3UNnx0U3VmC3LUGVj1mRo%3D' (2025-12-27)
  → 'github:NixOS/nixpkgs/39dee0b83ffffbe075a626b78bb20c95f7f68cac?narHash=sha256-CVvkU%2BGHzqpvSVt6/uW98fGtrt2tzvXGYawdrtHHiZ8%3D' (2026-01-03)
• Updated input 'released-nix-unstable':
    'github:nixos/nix/8093df5255572bde31f16287feabb155a218004e?narHash=sha256-D3kmmHHrntqLWAR0vu9psv0al0eTN3xcamB7WMKz4oU%3D' (2025-12-27)
  → 'github:nixos/nix/644be074e10dfa2463cf20788d8428b4cc652d01?narHash=sha256-Vb/M3oKvqEYtHv9GzJoc1ikSOxvkcPjygf48hhtBHqQ%3D' (2026-01-02)
• Updated input 'released-nixpkgs-stable':
    'github:NixOS/nixpkgs/f560ccec6b1116b22e6ed15f4c510997d99d5852?narHash=sha256-BASnpCLodmgiVn0M1MU2Pqyoz0aHwar/0qLkp7CjvSQ%3D' (2025-12-26)
  → 'github:NixOS/nixpkgs/64049ca74d63e971b627b5f3178d95642e61cedd?narHash=sha256-yA/CuWyqm%2BAQo2ivGy6PlYrjZBQm7jfbe461%2B4HF2fo%3D' (2026-01-02)
• Updated input 'released-nixpkgs-unstable':
    'github:NixOS/nixpkgs/3e2499d5539c16d0d173ba53552a4ff8547f4539?narHash=sha256-QEhk0eXgyIqTpJ/ehZKg9IKS7EtlWxF3N7DXy42zPfU%3D' (2025-12-25)
  → 'github:NixOS/nixpkgs/fb7944c166a3b630f177938e478f0378e64ce108?narHash=sha256-EgE0pxsrW9jp9YFMkHL9JMXxcqi/OoumPJYwf%2BOkucw%3D' (2026-01-02)
```

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