[Security release] Swagger UI 3.18.0 Released!

⚠️ This release contains security fixes. If your OpenAPI documents link to untrusted external URLs, you should upgrade.

Interface changes:

• You may experience issues with this version if you're importing Swagger UI in a non-browser environment (which we don't officially support). Consider loading JSDom beforehand, so that Swagger UI has the DOM APIs it needs access to.
• Links throughout Swagger UI now render with rel="noopener noreferrer", which blocks linked pages from accessing window.opener and the Referrer header.

Changelog:

• feature: "Send empty value" controls for allowEmptyValue parameters (via #4788)
• bugfix(security): anchor tag safety (via #4789)
• bugfix: default to empty object for pathItems in updateJsonSpec wrap-action (via #4785)