feat: pump protocol version to 6.0

Author: sorccu

terraform-registry-manifest.json

@@ -1,7 +1,8 @@
 {
   "version": 1,
   "metadata": {
-    "protocol_versions": ["5.0"]
+    "protocol_versions": [
+      "6.0"
+    ]
   }
-}
-
+}