docs: move CHANGELOG.md entry under SNAPSHOT

Signed-off-by: Piotr Płaczek <piotrpdev@gmail.com>

Author: piotrpdev

CHANGELOG.md

@@ -3,10 +3,12 @@
 Please enumerate all user-facing changes using format `<githib issue/pr number>: <short description>`, with changes ordered in reverse chronological order.
 
 ## SNAPSHOT
+
+* [#556](https://github.com/kroxylicious/kroxylicious-junit5-extension/pull/556): Upgrade to Testcontainers 2.0.2
+
 ## 0.13.0
 
 * [#544](https://github.com/kroxylicious/kroxylicious-junit5-extension/pull/544): Replace Keytool certificate generator by netty certificate builder
-* [#556](https://github.com/kroxylicious/kroxylicious-junit5-extension/pull/556): Upgrade to Testcontainers 2.0.2
 
 ### Changes, deprecations and removals