Notable differences from version 1.2.
- Support for Python 3.8, 3.9, 3.10.
- Remove the support for Python 3.5, 3.6.
- Patch variable to avoid naming problems and Xcode collision on MacOS & Linux.
- Fix g++ w/ambiguous isnan on Linux.
- Fix the PY_SSIZE_T_CLEAN macro for py3.10.