#142 a python wrapper for this library

[jiangshan song]

i wroted a py module that can call the function in python.
https://github.com/Jiangshan00001/pystm32flash

what i have done is :
1. copy the code from here to:
https://github.com/Jiangshan00001/pystm32flash/tree/main/libstm32flash_src
2. add CMakeLists.txt for cmake.
3. change the unistd.h include so that it could compile in msvc smoothly.
4. add two code libmain.c and libmain.h for library.
5. add a library target for python cffi call.
6. add one github action for the build in linux/macos/windows platform.
7. add a python wrapper.

write it here in case someone need it.