Updated swig_int_templates.hh to use PyUnicode_GET_LENGTH if available otherwise use PyUnicode_GET_SIZE for Python 3 as PyUnicode_GET_LENGTH is new in Python 3.3 and PyUnicode_GET_SIZE is deprecated in Python 3.3 and removed in Python 3.12.
coverage: 55.737% (-0.02%) from 55.755%
when pulling c91fde625dc4e768ce5107d900c94431880788c8 on 1613-pyunicode_get_size-removed-in-python-3.12
into 25b692d05595d3c05cd81e3ce9b02a3884bbab62 on master.
Updated swig_int_templates.hh to use PyUnicode_GET_LENGTH if available otherwise use PyUnicode_GET_SIZE for Python 3 as PyUnicode_GET_LENGTH is new in Python 3.3 and PyUnicode_GET_SIZE is deprecated in Python 3.3 and removed in Python 3.12.