Remove unused Microsoft.CSharp dependency

tests/ImageSharp.Tests/ImageSharp.Tests.csproj

@@ -28,7 +28,6 @@
   
   <ItemGroup>
     <PackageReference Include="Magick.NET-Q16-AnyCPU" Version="7.9.0.1" />
-    <PackageReference Include="Microsoft.CSharp" Version="4.5.0" />
     <PackageReference Include="System.Drawing.Common" Version="4.5.0" />
     <PackageReference Include="xunit" Version="2.3.1" />
     <PackageReference Include="xunit.runner.console" Version="2.3.1" />