chore(deps): group stylelint dependencies in renovate config

renovate.json

@@ -9,6 +9,13 @@
       "matchPackageNames": [
         "@grafana/faro-**"
       ]
+    },
+    {
+      "groupName": "stylelint",
+      "matchPackageNames": [
+        "stylelint",
+        "stylelint-config-standard"
+      ]
     }
   ]
 }