Make dependabot less noisy

Author: yrodiere

.github/dependabot.yml

@@ -1,6 +1,12 @@
 version: 2
 updates:
   - package-ecosystem: "maven"
-    directory: "/" # Location of package manifests
+    directory: "/"
     schedule:
-      interval: "daily"
+      interval: monthly
+    groups:
+      maven:
+        patterns:
+          - "*maven*plugin*"
+          - "*plexus*"
+          - "org.apache.maven*:*"