Add cooldown for CodeQL GitHub Actions updates

Author: jketema

.github/dependabot.yml

@@ -14,6 +14,8 @@ updates:
     directory: "/"
     schedule:
       interval: "daily"
+    cooldown:
+      default-days: 7
     ignore:
       - dependency-name: '*'
         update-types: ['version-update:semver-patch', 'version-update:semver-minor']