Update cdk in website to v9

[raquelarrojo]

Checklist (Check off all the items before submitting)

• [x] Build process is done without errors and all tests pass in /lib directory.
• [x] Self-reviewed the code prior to submitting.
• [x] Meets accessibility standards.
• [x] Added/updated documentation to /website as needed.
• [x] Added/updated tests as needed.

Purpose Update cdk version to 9 in website.

Description Cdk version updated to 9 in website.