This PR duplicates to the master branch the fixes and updates that were used to release versions 1.3.2 and 1.3.3:

• The script python/Doxy2PyDocStrings.py is run in the MacOSX job so that the inline documentation is now included in the Python wheels and source tarball.
• pypa/cibuildwheel is upgraded to its latest version 4.3 which allows to build wheels for Python 3.15.
• README.md is updated:
  • Wheels are provided for Python 3.15 since JSBSim 1.3.2
  • The Python API is documented at the url https://jsbsim-team.github.io/jsbsim/python
  • Cosmetic change to center the OSI logo in the Legal Notice section
• ManyLinux images are updated from manylinux2014 to manylinux_2_28:
  • According to PEP 599, the image manylinux2014 has reached end-of-life on June 30th, 2024. And even though PyPI still supports the uploading of packages built with manylinux2014, the build of JSBSim Python wheels fails for some versions of PyPy when using manylinux2014.
  • Following PEP 600 and its compliance check by one of PyPA maintainers the image manylinux_2_28 will be supported until May 31st, 2029 and will now be used to build JSBSim Python wheels for Linux.
• Add Doxygen documentation to the JSBSim namespace so that Doxygen takes global functions into account.