v1.3

Compatibility:

• Tested with Python 3.9.0

Additions:

• To help avoid compiler warning about uninitialized members, extra members
  are added to the PyModuleDef structure for Python 2: m_slots,
  m_traverse, m_clear and m_free.
  Under Python 2, they must be set to NULL (usually by continuing to leave
  them out).