add github actions updates

Author: vroldanbet

.github/dependabot.yml

@@ -8,3 +8,10 @@ updates:
     groups:
       npm:
         patterns: ["*"]
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "monthly"
+    groups:
+      github-actions:
+        patterns: ["*"]