Log Message:
py-flask: updated to 2.1.3

Version 2.1.3
- Inline some optional imports that are only used for certain CLI
  commands.
- Relax type annotation for ``after_request`` functions.
- ``instance_path`` for namespace packages uses the path closest to
  the imported submodule.
- Clearer error message when ``render_template`` and
  ``render_template_string`` are used outside an application context.