Update DiffEngine.Tests.csproj

Author: SimonCropp

src/DiffEngine.Tests/DiffEngine.Tests.csproj

@@ -11,7 +11,6 @@
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     <PackageReference Include="MarkdownSnippets.MsBuild" Version="24.5.0" PrivateAssets="all" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.3.2" />
-    <PackageReference Include="System.Drawing.Common" Version="5.0.0" />
     <PackageReference Include="Argon" Version="0.1.0" />
     <PackageReference Include="Xunit" Version="2.4.2" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.4.5" PrivateAssets="all" />