Upgrade example project to .NET 5.0

Author: colinangusmackay

src/Example/Example.csproj

@@ -2,12 +2,12 @@
 
     <PropertyGroup>
         <OutputType>Exe</OutputType>
-        <TargetFramework>netcoreapp3.1</TargetFramework>
+        <TargetFramework>net5.0</TargetFramework>
         <IsPackable>false</IsPackable>
     </PropertyGroup>
 
     <ItemGroup>
-      <PackageReference Include="Microsoft.Extensions.Configuration.Json" Version="3.1.15" />
+      <PackageReference Include="Microsoft.Extensions.Configuration.Json" Version="5.0.0" />
       <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="5.0.1" />
     </ItemGroup>