docs: update changelog to reflect k8s 1.22+ is required

Author: consideRatio

docs/source/changelog.md

@@ -12,7 +12,7 @@ and as we merge [breaking changes in pull
 requests](https://github.com/jupyterhub/zero-to-jupyterhub-k8s/pulls?q=is%3Apr+is%3Aclosed+label%3Abreaking),
 this list should be updated.
 
-- K8s 1.21 is now required.
+- K8s 1.22 is now required.
 - The Helm chart's provided images now use Python 3.11 instead of Python 3.9.
 
 ## 2.0