Update GitHub actions with dependabot too

.github/dependabot.yml

@@ -1,6 +1,16 @@
 version: 2
+
 updates:
-- package-ecosystem: maven
+  # Updates for workflow files
+  - package-ecosystem: "github-actions"
+    # Workflow files stored in the
+    # default location of `.github/workflows`
+    directory: "/"
+    schedule:
+      interval: "monthly"
+
+  # Maven project
+  - package-ecosystem: maven
     directory: "/"
     schedule:
       interval: weekly