Compiler warnings on main csharp samples solution

[johnataylor]

20>C:\private\v4\scratch\BotBuilder-Samples\samples\csharp_dotnetcore\45.state-management\StateMangementBot.csproj : warning NU1701: Package 'Microsoft.Azure.KeyVault.Core 1.0.0' was restored using '.NETFramework,Version=v4.6.1, .NETFramework,Version=v4.6.2, .NETFramework,Version=v4.7, .NETFramework,Version=v4.7.1, .NETFramework,Version=v4.7.2, .NETFramework,Version=v4.8' instead of the project target framework '.NETCoreApp,Version=v3.1'. This package may not be fully compatible with your project. 14>Facebook-Events-Bot -> C:\private\v4\scratch\BotBuilder-Samples\samples\csharp_dotnetcore\23.facebook-events\bin\Debug\netcoreapp3.1\Facebook-Events-Bot.dll

and then later:

33>C:\private\v4\scratch\BotBuilder-Samples\samples\csharp_dotnetcore\49.qnamaker-all-features\Dialog\QnAMakerBaseDialog.cs(41,56,41,78): warning CS1998: This async method lacks 'await' operators and will run synchronously. Consider using the 'await' operator to await non-blocking API calls, or 'await Task.Run(...)' to do CPU-bound work on a background thread. 33>C:\private\v4\scratch\BotBuilder-Samples\samples\csharp_dotnetcore\49.qnamaker-all-features\Dialog\QnAMakerBaseDialog.cs(58,65,58,91): warning CS1998: This async method lacks 'await' operators and will run synchronously. Consider using the 'await' operator to await non-blocking API calls, or 'await Task.Run(...)' to do CPU-bound work on a background thread.