Add Dependabot config for GitHub Actions

Author: swissspidy

.github/dependabot.yml

@@ -1,9 +1,18 @@
 version: 2
 updates:
 - package-ecosystem: composer
-  directory: "/"
+  directory: '/'
   schedule:
-    interval: daily
-    time: "12:00"
-    timezone: America/Los_Angeles
+    interval: monthly
   open-pull-requests-limit: 10
+- package-ecosystem: github-actions
+  directory: '/'
+  schedule:
+    interval: monthly
+  open-pull-requests-limit: 10
+  labels:
+    - Dependencies
+  groups:
+    github-actions:
+      patterns:
+        - '*'