Link the gdml2gm exe against Xerces-C, fixes CC7 build

GeoModelTools/GDMLtoGM/CMakeLists.txt

@@ -49,7 +49,7 @@ install( FILES ${HEADERS}
 # Create and install the gdml2gm executable.
 add_executable( gdml2gm gdml2gm/gdml2gm.cxx )
 target_link_libraries( gdml2gm PRIVATE
-    GeoModelXMLParser GeoModelCore::GeoModelKernel GeoModelIO::GeoModelWrite GeoModelIO::GeoModelDBManager GDMLtoGM )
+    GeoModelXMLParser GeoModelCore::GeoModelKernel GeoModelIO::GeoModelWrite GeoModelIO::GeoModelDBManager GDMLtoGM XercesC::XercesC )
 install( TARGETS gdml2gm
    EXPORT ${PROJECT_NAME}-export
    LIBRARY DESTINATION ${CMAKE_INSTALL_BINDIR}