Fix CI build issues. (#63)

* make program class public

* update SDKs

* remove experimental command line

* test: pin to 3.1.2 SDK

* need the full version number

Author: BillWagner

Beginners/myapp/myapp.csproj

@@ -2,12 +2,11 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>netcoreapp3.0</TargetFramework>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="System.CommandLine.DragonFruit" Version="0.3.0-alpha.19317.1" />
-    <PackageReference Include="System.CommandLine.Experimental" Version="0.3.0-alpha.19317.1" />
+    <PackageReference Include="System.CommandLine.DragonFruit" Version="0.3.0-alpha.20253.1" />
   </ItemGroup>
 
 </Project>

azure-pipelines.yml

@@ -16,7 +16,7 @@ jobs:
      displayName: 'Use .NET Core sdk'
      inputs:
        packageType: sdk
-       version: 3.1.x
+       version: 3.1.200
        installationPath: $(Agent.ToolsDirectory)/dotnet
    - task: UseDotNet@2
      displayName: 'Use .NET Core sdk'