Update dependency Gong-wpf-dragdrop to v4

Author: dependencyupdates[bot]

src/ServiceInsight/ServiceInsight.csproj

@@ -44,7 +44,7 @@
     <PackageReference Include="Autofac" Version="7.1.0" />
     <PackageReference Include="Autofac.Configuration" Version="6.0.0" />
     <PackageReference Include="AvalonEdit" Version="6.3.0.90" />
-    <PackageReference Include="Gong-wpf-dragdrop" Version="3.2.1" />
+    <PackageReference Include="Gong-wpf-dragdrop" Version="4.0.0" />
     <PackageReference Include="Humanizer" Version="2.14.1" />
     <PackageReference Include="Mindscape.Raygun4Net" Version="8.0.0" />
     <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />