Group GHA updates into a single PR

Author: hugovk

.github/renovate.json

@@ -5,5 +5,12 @@
     ],
     "labels": [
         "Dependency"
-    ]
+    ],
+    "packageRules": [
+        {
+            "groupName": "github-actions",
+            "matchManagers": ["github-actions"],
+            "separateMajorMinor": "false"
+        }
+  ]
 }