flake.lock: Update (#1924)

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

```
Flake lock file updates:

• Updated input 'flake-parts':
    'github:hercules-ci/flake-parts/5635c32d666a59ec9a55cab87e898889869f7b71?narHash=sha256-MhA7wmo/7uogLxiewwRRmIax70g6q1U/YemqTGoFHlM%3D' (2025-12-11)
  → 'github:hercules-ci/flake-parts/a34fae9c08a15ad73f295041fec82323541400a9?narHash=sha256-XswHlK/Qtjasvhd1nOa1e8MgZ8GS//jBoTqWtrS1Giw%3D' (2025-12-15)
• Updated input 'flake-parts/nixpkgs-lib':
    'github:nix-community/nixpkgs.lib/719359f4562934ae99f5443f20aa06c2ffff91fc?narHash=sha256-b0yj6kfvO8ApcSE%2BQmA6mUfu8IYG6/uU28OFn4PaC8M%3D' (2025-10-29)
  → 'github:nix-community/nixpkgs.lib/2075416fcb47225d9b68ac469a5c4801a9c4dd85?narHash=sha256-k00uTP4JNfmejrCLJOwdObYC9jHRrr/5M/a/8L2EIdo%3D' (2025-12-14)
• Updated input 'git-hooks-nix':
    'github:cachix/git-hooks.nix/09e45f2598e1a8499c3594fe11ec2943f34fe509?narHash=sha256-dixPWKiHzh80PtD0aLuxYNQ0xP%2B843dfXG/yM3OzaYQ%3D' (2025-12-11)
  → 'github:cachix/git-hooks.nix/b68b780b69702a090c8bb1b973bab13756cc7a27?narHash=sha256-t3T/xm8zstHRLx%2BpIHxVpQTiySbKqcQbK%2Br%2B01XVKc0%3D' (2025-12-16)
• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/fb812c98a7c867a8389d165c2bed5d7a08a41478?narHash=sha256-IRV8mWrHjhCkusB2X8oNPARfvJV95GJWapKX977fqUE%3D' (2025-12-13)
  → 'github:NixOS/nixpkgs/cab52b36dca5a5a368f05bd03fca0b543b5b9a3e?narHash=sha256-Svhx9lHB3wvxDu9UtxilofG3PZqKvfwUzarSIvuGO5g%3D' (2025-12-20)
• Updated input 'released-nix-unstable':
    'github:nixos/nix/a6eb2e91b70c3ad874c494fe169a498dc432dd44?narHash=sha256-SaeLFPG1EkwS6OEXCuXE3m%2BOzhrLf5x0rO/La4mItag%3D' (2025-12-13)
  → 'github:nixos/nix/b6dd17d6f2dbed0a5966f40685fd455c4feb6a57?narHash=sha256-YL8nL9rYblWmDlp8StmJYlq58xSPWdwLJDWU0FFbiMI%3D' (2025-12-20)
• Updated input 'released-nixpkgs-stable':
    'github:NixOS/nixpkgs/09eb77e94fa25202af8f3e81ddc7353d9970ac1b?narHash=sha256-mSD5Ob7a%2BT2RNjvPvOA1dkJHGVrNVl8ZOrAwBjKBDQo%3D' (2025-12-09)
  → 'github:NixOS/nixpkgs/c6f52ebd45e5925c188d1a20119978aa4ffd5ef6?narHash=sha256-m5KWt1nOm76ILk/JSCxBM4MfK3rYY7Wq9/TZIIeGnT8%3D' (2025-12-15)
• Updated input 'released-nixpkgs-unstable':
    'github:NixOS/nixpkgs/2fbfb1d73d239d2402a8fe03963e37aab15abe8b?narHash=sha256-9VvC20PJPsleGMewwcWYKGzDIyjckEz8uWmT0vCDYK0%3D' (2025-12-11)
  → 'github:NixOS/nixpkgs/c6245e83d836d0433170a16eb185cefe0572f8b8?narHash=sha256-G/WVghka6c4bAzMhTwT2vjLccg/awmHkdKSd2JrycLc%3D' (2025-12-18)
```

### Running GitHub Actions on this PR

GitHub Actions will not run workflows on pull requests which are opened
by a GitHub Action.

**To run GitHub Actions workflows on this PR, close and re-open this
pull request.**

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: github-actions[bot]