chore(dependabot): batch github-actions and maven updates monthly (#572)

Author: johnoliver

.github/dependabot.yml

@@ -1,7 +1,19 @@
 version: 2
 updates:
-- package-ecosystem: github-actions
-  directory: "/"
-  schedule:
-    interval: daily
-  open-pull-requests-limit: 10
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "monthly"
+    groups:
+      monthly-batch:
+        patterns:
+          - "*"
+
+  - package-ecosystem: "maven"
+    directory: "/"
+    schedule:
+      interval: "monthly"
+    groups:
+      monthly-batch:
+        patterns:
+          - "*"