build(nix): update flake.lock

Flake lock file updates:

• Updated input 'flake-utils':
    'github:numtide/flake-utils/5aed5285a952e0b949eb3ba02c12fa4fcfef535f' (2022-11-02)
  → 'github:numtide/flake-utils/a1720a10a6cfe8234c0e93907ffe81be440f4cef' (2023-05-31)
• Added input 'flake-utils/systems':
    'github:nix-systems/default/da67096a3b9bf56a91d16901293e51ba5b49a27e' (2023-04-09)
• Updated input 'nixpkgs':
    'github:nixos/nixpkgs/abe7316dd51a313ce528972b104f4f04f56eefc4' (2023-04-14)
  → 'github:nixos/nixpkgs/a64b73e07d4aa65cfcbda29ecf78eaf9e72e44bd' (2023-06-08)

contrib/flake.lock

@@ -1,12 +1,15 @@
 {
   "nodes": {
     "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
       "locked": {
-        "lastModified": 1667395993,
-        "narHash": "sha256-nuEHfE/LcWyuSWnS8t12N1wc105Qtau+/OdUAjtQ0rA=",
+        "lastModified": 1685518550,
+        "narHash": "sha256-o2d0KcvaXzTrPRIo0kOLV0/QXHhDQ5DTi+OxcjO8xqY=",
         "owner": "numtide",
         "repo": "flake-utils",
-        "rev": "5aed5285a952e0b949eb3ba02c12fa4fcfef535f",
+        "rev": "a1720a10a6cfe8234c0e93907ffe81be440f4cef",
         "type": "github"
       },
       "original": {
@@ -17,11 +20,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1681465517,
-        "narHash": "sha256-EasJh15/jcJNAHtq2SGbiADRXteURAnQbj1NqBoKkzU=",
+        "lastModified": 1686226982,
+        "narHash": "sha256-nLuiPoeiVfqqzeq9rmXxpybh77VS37dsY/k8N2LoxVg=",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "abe7316dd51a313ce528972b104f4f04f56eefc4",
+        "rev": "a64b73e07d4aa65cfcbda29ecf78eaf9e72e44bd",
         "type": "github"
       },
       "original": {
@@ -36,6 +39,21 @@
         "flake-utils": "flake-utils",
         "nixpkgs": "nixpkgs"
       }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
     }
   },
   "root": "root",