When a maintenance update is executed, the update itself does not update the extension versions that are used automatically.
The reason for this is that user schemas and functions can and do often rely on specific versions of an extension being used, if we change the underlying assumption behind that we would be breaking user code.
Instead the users need to upgrade the extensions themselves explicitly. This sort of behavior is commonly true even if you were to run PostgreSQL on your own and just upgrade the package version of an extension to be newer, that won't update the extension version in the database(s) automatically either.
So to actually run the update, please run:
ALTER EXTENSION extensionname UPDATE;
To update to the very latest version that is available.