chore(deps): bump the nix group with 2 updates

Bumps the nix group with 2 updates: [devenv](https://github.com/cachix/devenv) and [nixpkgs](https://github.com/NixOS/nixpkgs).


Updates `devenv` from `a60ff7d` to `72e18a7`
- [Release notes](https://github.com/cachix/devenv/releases)
- [Commits](https://github.com/cachix/devenv/compare/a60ff7da8843686d06b4c6646846024d97138da8...72e18a7a33a9fe7b157a46f8eea58f424a511f14)

Updates `nixpkgs` from `6510408` to `7fd4004`
- [Commits](https://github.com/NixOS/nixpkgs/compare/6510408d147d8c5e6d76043e899e9251756f6a75...7fd4004d0511991fff3a0524856a9be09e28c5f0)

---
updated-dependencies:
- dependency-name: devenv
  dependency-version: 72e18a7a33a9fe7b157a46f8eea58f424a511f14
  dependency-type: direct:production
  dependency-group: nix
- dependency-name: nixpkgs
  dependency-version: 7fd4004d0511991fff3a0524856a9be09e28c5f0
  dependency-type: direct:production
  dependency-group: nix
...

Signed-off-by: dependabot[bot] <support@github.com>

flake.lock

@@ -64,11 +64,11 @@
         "rust-overlay": "rust-overlay"
       },
       "locked": {
-        "lastModified": 1791785848,
-        "narHash": "sha256-8hOkttkgaVPCKwLHK5T2XbfBIj1k4G6xO1r4UVYm5aA=",
+        "lastModified": 1791818779,
+        "narHash": "sha256-A605ntzBcnhqZ5UPVUkoM/WVTdqffQhTbtITWGEbTEU=",
         "owner": "cachix",
         "repo": "devenv",
-        "rev": "a60ff7da8843686d06b4c6646846024d97138da8",
+        "rev": "72e18a7a33a9fe7b157a46f8eea58f424a511f14",
         "type": "github"
       },
       "original": {
@@ -278,11 +278,11 @@
     },
     "nixpkgs_2": {
       "locked": {
-        "lastModified": 1791594108,
-        "narHash": "sha256-XK4KceonkwD8LuMAt/vNrz982mXJM5jeHAxMwsUXXAQ=",
+        "lastModified": 1791734076,
+        "narHash": "sha256-i5qk1kLiit98rRbh1AXmWBNT9QXC/y4l5Wk/u5EdpDQ=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "6510408d147d8c5e6d76043e899e9251756f6a75",
+        "rev": "7fd4004d0511991fff3a0524856a9be09e28c5f0",
         "type": "github"
       },
       "original": {