Updated test project framework.

Author: Travis Illig

test/Autofac.Extras.FakeItEasy.Test/Autofac.Extras.FakeItEasy.Test.csproj

@@ -21,12 +21,12 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.0.0" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="2.2.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.7.2" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.3.1" />
     <PackageReference Include="StyleCop.Analyzers" Version="1.1.0-beta006">
       <PrivateAssets>All</PrivateAssets>
     </PackageReference>
-    <PackageReference Include="xunit" Version="2.2.0" />
+    <PackageReference Include="xunit" Version="2.3.1" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\src\Autofac.Extras.FakeItEasy\Autofac.Extras.FakeItEasy.csproj" />