Remove unused nuget package reference

Author: amaitland

CefSharp.Extensions.Test/CefSharp.Extensions.Test.csproj

@@ -12,7 +12,6 @@
     <PackageReference Include="Nito.AsyncEx.Context" Version="5.0.0" />
     <PackageReference Include="xunit" Version="2.4.0" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.4.0" />
-    <PackageReference Include="coverlet.collector" Version="1.2.0" />
   </ItemGroup>
 
   <ItemGroup>