chore(deps): bump nixpkgs from 148bab9 to 6438090 in /nix (#5907)

Bumps [nixpkgs](https://github.com/NixOS/nixpkgs) from `148bab9` to `6438090`.
- [Commits](148bab9c1c...643809054d)

---
updated-dependencies:
- dependency-name: nixpkgs
  dependency-version: 643809054d65fdd466a63e3155b8c498cb483c04
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

nix/flake.lock

@@ -20,11 +20,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1785571196,
-        "narHash": "sha256-KoTsyMQqnXQZq8deCEnu4QkyldkwH/bpMMhUcfMdGIw=",
+        "lastModified": 1785967620,
+        "narHash": "sha256-IItrdb7Puk05RqOBWZYFC5X6Wl1sJmCfh5MWVHw5iMM=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "148bab9c1c3c53136ecb44a6ea356a0ed5b39b06",
+        "rev": "b7c2ada94fe99c15b0dbcf4d11fd7850b957a436",
         "type": "github"
       },
       "original": {