[ROS2]missing <buildtool_depend>ament_python</buildtool_depend> in package.xml

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I followed the tutorial:Creating your first ROS 2 package
I entered the following command in my terminal:

ros2 pkg create --build-type ament_python test_pkg_py

I opened package.xmlthat ros2 pkg create automatically generated:

<?xml version="1.0"?>
<?xml-model href="http://download.ros.org/schema/package_format3.xsd" schematypens="http://www.w3.org/2001/XMLSchema"?>
<package format="3">
  <name>pubsub_py</name>
  <version>0.0.0</version>
  <description>TODO: Package description</description>
  <maintainer email="sylvia@todo.todo">sylvia</maintainer>
  <license>TODO: License declaration</license>

  <test_depend>ament_copyright</test_depend>
  <test_depend>ament_flake8</test_depend>
  <test_depend>ament_pep257</test_depend>
  <test_depend>python3-pytest</test_depend>

  <export>
    <build_type>ament_python</build_type>
  </export>
</package>

The content is different from tutorial:Creating your first ROS 2 package
My package.xml misses the following command:

<buildtool_depend>ament_python</buildtool_depend>

Did I miss any dependecies? ROS environment: Foxy OS: Ubuntu20.04