Update nuget version to 1.20
Update nuget version to 1.20

Clairety/ConnectMe,xiangyan99/BotBuilder,yakumo/BotBuilder,msft-shahins/BotBuilder,msft-shahins/BotBuilder,stevengum97/BotBuilder,mmatkow/BotBuilder,yakumo/BotBuilder,yakumo/BotBuilder,mmatkow/BotBuilder,xiangyan99/BotBuilder,dr-em/BotBuilder,dr-em/BotBuilder,dr-em/BotBuilder,stevengum97/BotBuilder,msft-shahins/BotBuilder,Clairety/ConnectMe,mmatkow/BotBuilder,Clairety/ConnectMe,stevengum97/BotBuilder,stevengum97/BotBuilder,Clairety/ConnectMe,mmatkow/BotBuilder,yakumo/BotBuilder,msft-shahins/BotBuilder,xiangyan99/BotBuilder,xiangyan99/BotBuilder,dr-em/BotBuilder