Fix for build error with boost::prior

[arn13]

According to this issue boost::prior has bee moved. This leads to an error when trying to build the package:

error: ‘prior’ is not a member of ‘boost’; did you mean ‘boost::mpl::prior’?
  144 |        k.construct_segment_3_object()(*pts.begin(), *boost::prior(pts.end())));
      |                                      

The fix mentioned in the issue above works to resolve this error.

#include <boost/next_prior.hpp> has to be added into Plane_3_Triangle_3_intersection.h