Update required dotnet to 3.1.100 (#41113)
Update required dotnet to 3.1.100 (#41113)

* Update required dotnet to 3.1.100

* Update required VS to 16.4

aelij/roslyn,panopticoncentral/roslyn,davkean/roslyn,jmarolf/roslyn,stephentoub/roslyn,mavasani/roslyn,diryboy/roslyn,KirillOsenkov/roslyn,physhi/roslyn,heejaechang/roslyn,CyrusNajmabadi/roslyn,brettfo/roslyn,physhi/roslyn,davkean/roslyn,tmat/roslyn,reaction1989/roslyn,mgoertz-msft/roslyn,diryboy/roslyn,physhi/roslyn,shyamnamboodiripad/roslyn,mgoertz-msft/roslyn,dotnet/roslyn,heejaechang/roslyn,wvdd007/roslyn,shyamnamboodiripad/roslyn,eriawan/roslyn,abock/roslyn,dotnet/roslyn,jasonmalinowski/roslyn,brettfo/roslyn,mgoertz-msft/roslyn,KevinRansom/roslyn,bartdesmet/roslyn,ErikSchierboom/roslyn,AmadeusW/roslyn,brettfo/roslyn,panopticoncentral/roslyn,weltkante/roslyn,diryboy/roslyn,abock/roslyn,gafter/roslyn,AlekseyTs/roslyn,panopticoncentral/roslyn,tannergooding/roslyn,reaction1989/roslyn,KirillOsenkov/roslyn,tmat/roslyn,stephentoub/roslyn,heejaechang/roslyn,CyrusNajmabadi/roslyn,AmadeusW/roslyn,jmarolf/roslyn,reaction1989/roslyn,mavasani/roslyn,AlekseyTs/roslyn,aelij/roslyn,ErikSchierboom/roslyn,dotnet/roslyn,mavasani/roslyn,eriawan/roslyn,KevinRansom/roslyn,jasonmalinowski/roslyn,gafter/roslyn,KevinRansom/roslyn,agocke/roslyn,shyamnamboodiripad/roslyn,CyrusNajmabadi/roslyn,gafter/roslyn,ErikSchierboom/roslyn,eriawan/roslyn,agocke/roslyn,davkean/roslyn,genlu/roslyn,weltkante/roslyn,sharwell/roslyn,bartdesmet/roslyn,AlekseyTs/roslyn,stephentoub/roslyn,abock/roslyn,tmat/roslyn,agocke/roslyn,sharwell/roslyn,wvdd007/roslyn,weltkante/roslyn,tannergooding/roslyn,AmadeusW/roslyn,KirillOsenkov/roslyn,wvdd007/roslyn,aelij/roslyn,tannergooding/roslyn,genlu/roslyn,jmarolf/roslyn,genlu/roslyn,sharwell/roslyn,jasonmalinowski/roslyn,bartdesmet/roslyn