flake.lock: Update

Flake lock file updates:

• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/c0b0e0fddf73fd517c3471e546c0df87a42d53f4?narHash=sha256-coBu0ONtFzlwwVBzmjacUQwj3G%2BlybcZ1oeNSQkgC0M%3D' (2025-12-28)
  → 'github:NixOS/nixpkgs/9f0c42f8bc7151b8e7e5840fb3bd454ad850d8c5?narHash=sha256-UWYqmD7JFBEDBHWYcqE6s6c77pWdcU/i%2BbwD6XxMb8A%3D' (2026-01-05)

flake.lock

@@ -2,11 +2,11 @@
   "nodes": {
     "nixpkgs": {
       "locked": {
-        "lastModified": 1766902085,
-        "narHash": "sha256-coBu0ONtFzlwwVBzmjacUQwj3G+lybcZ1oeNSQkgC0M=",
+        "lastModified": 1767640445,
+        "narHash": "sha256-UWYqmD7JFBEDBHWYcqE6s6c77pWdcU/i+bwD6XxMb8A=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "c0b0e0fddf73fd517c3471e546c0df87a42d53f4",
+        "rev": "9f0c42f8bc7151b8e7e5840fb3bd454ad850d8c5",
         "type": "github"
       },
       "original": {