Added build platform x64
Added build platform x64

Trying solution found in https://github.com/dotnet/msbuild/issues/5134
valadas/Dnn.Platform,dnnsoftware/Dnn.Platform,valadas/Dnn.Platform,nvisionative/Dnn.Platform,bdukes/Dnn.Platform,dnnsoftware/Dnn.Platform,bdukes/Dnn.Platform,valadas/Dnn.Platform,mitchelsellers/Dnn.Platform,mitchelsellers/Dnn.Platform,valadas/Dnn.Platform,mitchelsellers/Dnn.Platform,mitchelsellers/Dnn.Platform,dnnsoftware/Dnn.Platform,valadas/Dnn.Platform,dnnsoftware/Dnn.Platform,mitchelsellers/Dnn.Platform,bdukes/Dnn.Platform,nvisionative/Dnn.Platform,bdukes/Dnn.Platform,nvisionative/Dnn.Platform,dnnsoftware/Dnn.Platform