chore(deps): bump nixpkgs from ffb3c9b to 56c02bc in /nix (#5997)

Bumps [nixpkgs](https://github.com/NixOS/nixpkgs) from `ffb3c9b` to `56c02bc`.
- [Commits](https://github.com/NixOS/nixpkgs/compare/ffb3c9b700e759be2ef13237c9d8f953b32a1e46...56c02bc00adcf003215cc4bd996d6efaf4cff188)

---
updated-dependencies:
- dependency-name: nixpkgs
  dependency-version: 56c02bc00adcf003215cc4bd996d6efaf4cff188
  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": 1787135253,
-        "narHash": "sha256-RD2kNWCG+Bjo6h+JVjWVNntZs2GtRoeY2xHjts/FNkA=",
+        "lastModified": 1787498568,
+        "narHash": "sha256-9i/VTdusq/+NM/tz+J1Re+ojkMB8MBf0QshnYfzHz30=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "ffb3c9b700e759be2ef13237c9d8f953b32a1e46",
+        "rev": "56c02bc00adcf003215cc4bd996d6efaf4cff188",
         "type": "github"
       },
       "original": {