CMake: Fix case sensitivity of SWIG package
CMake: Fix case sensitivity of SWIG package

On case-sensitive file systems, the SWIG module is in all caps.

mtCarto/PDAL,DougFirErickson/PDAL,mtCarto/PDAL,jwomeara/PDAL,mpgerlek/PDAL-old,radiantbluetechnologies/PDAL,Sciumo/PDAL,lucadelu/PDAL,radiantbluetechnologies/PDAL,boundlessgeo/PDAL,mpgerlek/PDAL-old,mtCarto/PDAL,Sciumo/PDAL,jwomeara/PDAL,radiantbluetechnologies/PDAL,DougFirErickson/PDAL,jwomeara/PDAL,Sciumo/PDAL,boundlessgeo/PDAL,Sciumo/PDAL,boundlessgeo/PDAL,DougFirErickson/PDAL,lucadelu/PDAL,lucadelu/PDAL,mtCarto/PDAL,mpgerlek/PDAL-old,DougFirErickson/PDAL,boundlessgeo/PDAL,radiantbluetechnologies/PDAL,lucadelu/PDAL,mpgerlek/PDAL-old,jwomeara/PDAL