netstandard2.1 enable $(LangVersion) $(BotSharpVersion) $(GeneratePackageOnBuild) $(SolutionDir)packages PreserveNewest PreserveNewest PreserveNewest PreserveNewest PreserveNewest PreserveNewest PreserveNewest PreserveNewest PreserveNewest PreserveNewest PreserveNewest PreserveNewest PreserveNewest PreserveNewest PreserveNewest PreserveNewest PreserveNewest PreserveNewest PreserveNewest