Renovate: group GitHub actions updates

Author: 31ch

renovate.json

@@ -2,5 +2,16 @@
   "$schema": "https://docs.renovatebot.com/renovate-schema.json",
   "extends": [
     "config:recommended"
+  ],
+  "git-submodules": {
+    "enabled": true
+  },
+  "packageRules": [
+    {
+      "groupName": "GitHub Actions",
+      "matchManagers": [
+        "github-actions"
+      ]
+    }
   ]
-}
+}