update github CI workflows (#83)

Author: OriolAbril

.github/dependabot.yml

@@ -3,4 +3,10 @@ updates:
 - package-ecosystem: "github-actions"
   directory: "/"
   schedule:
-    interval: "weekly"
+    interval: "monthly"
+  cooldown:
+    default-days: 14
+  groups:
+    actions:
+      patterns:
+        - "*"