flake.nix: Use patched nixpkgs for carbon

flake.lock

@@ -532,6 +532,22 @@
         "type": "github"
       }
     },
+    "nixpkgs-carbon": {
+      "locked": {
+        "lastModified": 1751206202,
+        "narHash": "sha256-VjK8pEv4cfDpCTh4KW1go98kP25j7KdTNEce342Bh/Y=",
+        "owner": "clerie",
+        "repo": "nixpkgs",
+        "rev": "ac4ac98609c1b30c378458ab7207a9a5b5148457",
+        "type": "github"
+      },
+      "original": {
+        "owner": "clerie",
+        "ref": "clerie/always-setup-netdevs",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
     "nixpkgs-regression": {
       "locked": {
         "lastModified": 1643052045,
@@ -731,6 +747,7 @@
         "nixos-hardware": "nixos-hardware",
         "nixpkgs": "nixpkgs_5",
         "nixpkgs-0dc1c7": "nixpkgs-0dc1c7",
+        "nixpkgs-carbon": "nixpkgs-carbon",
         "nurausstieg": "nurausstieg",
         "rainbowrss": "rainbowrss",
         "scan-to-gpg": "scan-to-gpg",

flake.nix

@@ -1,6 +1,7 @@
 {
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    nixpkgs-carbon.url = "github:clerie/nixpkgs/clerie/always-setup-netdevs";
     # for etesync-dav
     nixpkgs-0dc1c7.url = "github:NixOS/nixpkgs/0dc1c7294c13f5d1dd6eccab4f75d268d7296efe";
     nixos-hardware.url = "github:NixOS/nixos-hardware/master";