CI: changing to monthly dependabot

Author: bsipocz

.github/dependabot.yml

@@ -5,7 +5,13 @@
 
 version: 2
 updates:
-  - package-ecosystem: "github-actions" # See documentation for possible values
-    directory: ".github/workflows" # Location of package manifests
+  - package-ecosystem: "github-actions"
+    directory: "/"
     schedule:
-      interval: "weekly"
+      interval: "monthly"
+    groups:
+      actions:
+        patterns:
+          - "*"
+    labels:
+      - "no-changelog-entry-needed"