Correct version added for new Namespaced log levels feature

The PR that added this was opened before 3.1.0rc, but it didn't get merged
until after the branch point, so given it's a new feature, not a bug fix, this
won't be released until 3.2.0

Author: ashb

airflow-core/src/airflow/config_templates/config.yml

@@ -812,7 +812,7 @@ logging:
         The logger names are viewable in task logs (as the "source" attribute), or in server components by
         including ``%(name)s`` in your format string, or in the between ``[]`` after the message in the
         default format.
-      version_added: 3.1.0
+      version_added: 3.2.0
       type: string
       example: "sqlalchemy=INFO sqlalchemy.engine=DEBUG, botocor"
       default: ~