Add:cooldown period(15 days)

Wait 15 days between dependency update PRs to reduce noise

Author: wbatchayon

.github/dependabot.yml

@@ -1,6 +1,9 @@
 version: 2
+# Cooldown: Wait 15 days between dependency update PRs to reduce noise
 updates:
   - package-ecosystem: "gomod" # See documentation for possible values
     directory: "/" # Location of package manifests
     schedule:
       interval: "daily"
+    cooldown:
+      default-days: 15