ENH: Update GDCM upstream repository to GitHub
ENH: Update GDCM upstream repository to GitHub

The SourceForge clone fails.

LucasGandel/ITK,thewtex/ITK,Kitware/ITK,Kitware/ITK,LucasGandel/ITK,thewtex/ITK,thewtex/ITK,Kitware/ITK,hjmjohnson/ITK,BRAINSia/ITK,vfonov/ITK,hjmjohnson/ITK,richardbeare/ITK,LucasGandel/ITK,richardbeare/ITK,vfonov/ITK,vfonov/ITK,thewtex/ITK,Kitware/ITK,LucasGandel/ITK,BRAINSia/ITK,vfonov/ITK,hjmjohnson/ITK,thewtex/ITK,richardbeare/ITK,InsightSoftwareConsortium/ITK,InsightSoftwareConsortium/ITK,richardbeare/ITK,Kitware/ITK,richardbeare/ITK,hjmjohnson/ITK,BRAINSia/ITK,richardbeare/ITK,richardbeare/ITK,LucasGandel/ITK,BRAINSia/ITK,BRAINSia/ITK,Kitware/ITK,hjmjohnson/ITK,thewtex/ITK,BRAINSia/ITK,vfonov/ITK,Kitware/ITK,LucasGandel/ITK,LucasGandel/ITK,InsightSoftwareConsortium/ITK,vfonov/ITK,vfonov/ITK,InsightSoftwareConsortium/ITK,vfonov/ITK,BRAINSia/ITK,InsightSoftwareConsortium/ITK,hjmjohnson/ITK,LucasGandel/ITK,thewtex/ITK,hjmjohnson/ITK,InsightSoftwareConsortium/ITK,vfonov/ITK,InsightSoftwareConsortium/ITK