chore: update ImageSharp version to 1.0.4

fixes #191

Author: leo2d

PdfSharpCore/PdfSharpCore.csproj

@@ -38,7 +38,7 @@ PdfSharpCore is a partial port of PdfSharp.Xamarin for .NET Core Additionally Mi
     <Folder Include="Resources\images\" />
   </ItemGroup>
   <ItemGroup>
-    <PackageReference Include="SixLabors.ImageSharp" Version="1.0.0" />
+    <PackageReference Include="SixLabors.ImageSharp" Version="1.0.4" />
     <PackageReference Include="SixLabors.Fonts" Version="1.0.0-beta0013" />
   </ItemGroup>