Update dependencies from...

Update dependencies from https://dev.azure.com/dnceng/internal/_git/dotnet-wpf-int build 20200510.2 (#2974)

- Microsoft.DotNet.Wpf.DncEng: 5.0.0-preview.5.20228.3 -> 5.0.0-preview.5.20260.2
Co-authored-by: Ndotnet-maestro[bot] <dotnet-maestro[bot]@users.noreply.github.com>

eng/Version.Details.xml

@@ -71,9 +71,9 @@
       <Uri>https://github.com/dotnet/runtime</Uri>
       <Sha>bd34833c96dcccb9c5a7366fb687f160460be3ae</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.DotNet.Wpf.DncEng" Version="5.0.0-preview.5.20228.3">
+    <Dependency Name="Microsoft.DotNet.Wpf.DncEng" Version="5.0.0-preview.5.20260.2">
       <Uri>https://dev.azure.com/dnceng/internal/_git/dotnet-wpf-int</Uri>
-      <Sha>40603134a33b35fcd3658e70340b7feab233471c</Sha>
+      <Sha>8526d5c71adc1d32dc3f1bef21bcd799fa284742</Sha>
     </Dependency>
     <Dependency Name="System.IO.Packaging" Version="5.0.0-preview.5.20228.3" CoherentParentDependency="Microsoft.Private.Winforms">
       <Uri>https://github.com/dotnet/runtime</Uri>

eng/Versions.props

@@ -96,6 +96,6 @@
     <SystemReflectionMetadataLoadContextPackage>System.Reflection.MetadataLoadContext</SystemReflectionMetadataLoadContextPackage>
   </PropertyGroup>
   <PropertyGroup>
-    <MicrosoftDotNetWpfDncEngVersion>5.0.0-preview.5.20228.3</MicrosoftDotNetWpfDncEngVersion>
+    <MicrosoftDotNetWpfDncEngVersion>5.0.0-preview.5.20260.2</MicrosoftDotNetWpfDncEngVersion>
   </PropertyGroup>
 </Project>