meta(changelog): Update changelog for 9.21.0

Author: andreiborza

CHANGELOG.md

@@ -10,6 +10,13 @@
 
 - "You miss 100 percent of the chances you don't take. — Wayne Gretzky" — Michael Scott
 
+## 9.21.0
+
+- docs: Fix v7 migration link ([#14629](https://github.com/getsentry/sentry-javascript/pull/14629))
+- feat(node): Vendor in `@fastify/otel` ([#16328](https://github.com/getsentry/sentry-javascript/pull/16328))
+- fix(nestjs): Handle multiple `OnEvent` decorators ([#16306](https://github.com/getsentry/sentry-javascript/pull/16306))
+- fix(node): Avoid creating breadcrumbs for suppressed requests ([#16285](https://github.com/getsentry/sentry-javascript/pull/16285))
+
 Work in this release was contributed by @phthhieu. Thank you for your contribution!
 
 ## 9.20.0