Move changelog entry to "Unreleased"

CHANGES.md

@@ -67,6 +67,7 @@
  than requiring them to be passed separately via the `--extra_package` option
  (Python) ([#23684](https://github.com/apache/beam/pull/23684)).
 * Pipeline Resource Hints now supported via `--resource_hints` flag (Go) ([#23990](https://github.com/apache/beam/pull/23990)).
+* Make Python SDK containers reusable on portable runners by installing dependencies to temporary venvs ([BEAM-12792](https://issues.apache.org/jira/browse/BEAM-12792)).
 
 ## Breaking Changes
 
@@ -363,7 +364,6 @@
 * Added support for cloudpickle as a pickling library for Python SDK ([BEAM-8123](https://issues.apache.org/jira/browse/BEAM-8123)). To use cloudpickle, set pipeline option: --pickler_lib=cloudpickle
 * Added option to specify triggering frequency when streaming to BigQuery (Python) ([BEAM-12865](https://issues.apache.org/jira/browse/BEAM-12865)).
 * Added option to enable caching uploaded artifacts across job runs for Python Dataflow jobs ([BEAM-13459](https://issues.apache.org/jira/browse/BEAM-13459)). To enable, set pipeline option: --enable_artifact_caching, this will be enabled by default in a future release.
-* Make Python SDK containers reusable on portable runners by installing dependencies to temporary venvs ([BEAM-12792](https://issues.apache.org/jira/browse/BEAM-12792)).
 
 ## Breaking Changes