chore(flake): update nixvim

Nixvim added a `systems` input which we override, also this commit has
the `hunk.nvim` plugin which we want.

flake.lock

@@ -339,14 +339,17 @@
           "flake-parts"
         ],
         "nixpkgs": "nixpkgs_2",
-        "nuschtosSearch": []
+        "nuschtosSearch": [],
+        "systems": [
+          "systems"
+        ]
       },
       "locked": {
-        "lastModified": 1746965641,
-        "narHash": "sha256-6+Cn5aMDSWvsk4nOXmea3whAI4v+PjYaEpcDkTEAlXc=",
+        "lastModified": 1747083534,
+        "narHash": "sha256-r88FEbKX1HLTovPFt1QHxzZDV7D4TGHhYlJcHmK7hYk=",
         "owner": "nix-community",
         "repo": "nixvim",
-        "rev": "02a85bd29333ce9fbde0d2c57a2378f47205bb21",
+        "rev": "ff0ccdf572ad6700a2a29a82cc5d17db29708988",
         "type": "github"
       },
       "original": {

flake.nix

@@ -39,6 +39,7 @@
       url = "github:nix-community/nixvim";
       inputs = {
         flake-parts.follows = "flake-parts";
+        systems.follows = "systems";
         # disable optional inputs
         nuschtosSearch.follows = "";
       };