Prepare release 4.2.0

Author: ste93cry

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+## 4.2.0 (2021-08-12)
+
 - Log the bus name, receiver name and message class name as event tags when using Symfony Messenger (#492)
 - Make the transport factory configurable in the bundle's config (#504)
 - Add the `sentry_trace_meta()` Twig function to print the `sentry-trace` HTML meta tag (#510)