Include package Microsoft.DiaSymReader.Converter.Xml only in debug builds as it is only used for debug features.

ILSpy/ILSpy.csproj

@@ -49,7 +49,6 @@
 
   <ItemGroup>
     <PackageReference Include="AvalonEdit" Version="6.0.0-rc1" />
-    <PackageReference Include="Microsoft.DiaSymReader.Converter.Xml" Version="1.1.0-beta1-63314-01" />
     <PackageReference Include="Microsoft.VisualStudio.Composition" Version="15.5.23" />
     <PackageReference Include="Mono.Cecil" Version="0.10.3" />
     <PackageReference Include="OSVersionHelper" Version="1.0.11" />
@@ -60,6 +59,10 @@
     <ProjectReference Include="..\SharpTreeView\ICSharpCode.TreeView.csproj" />
   </ItemGroup>
 
+  <ItemGroup Condition="'$(Configuration)' == 'Debug'">
+    <PackageReference Include="Microsoft.DiaSymReader.Converter.Xml" Version="1.1.0-beta1-63314-01" />
+  </ItemGroup>
+    
   <ItemGroup>
     <ApplicationDefinition Include="App.xaml" />
   </ItemGroup>