Use latest SWIG instead of old versions when the newer versions are fixed.

There are bugs in the latest versions of SWIG that prevent roadrunner from being compiled, which is why currently we set the SWIG version to 4.0.2.  However, ideally we would just use the latest version instead.  Monitor https://github.com/swig/swig/issues/3115 and https://github.com/swig/swig/issues/3109 to see if they get fixed.
