Update dependencies from...

Update dependencies from https://dev.azure.com/dnceng/internal/_git/dotnet-wpf-int build 20200530.2 (#3072)

Microsoft.DotNet.Wpf.DncEng
 From Version 5.0.0-preview.6.20279.2 -> To Version 5.0.0-preview.6.20280.2
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>35aa7989884dda8347899dcea162daf0c9318051</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.DotNet.Wpf.DncEng" Version="5.0.0-preview.6.20279.2">
+    <Dependency Name="Microsoft.DotNet.Wpf.DncEng" Version="5.0.0-preview.6.20280.2">
       <Uri>https://dev.azure.com/dnceng/internal/_git/dotnet-wpf-int</Uri>
-      <Sha>73238dc8ed6db154fb36ef57a8edd115125aadb1</Sha>
+      <Sha>cdfc3a8a2d497e6aedc4a176942b59924d8faaf9</Sha>
     </Dependency>
     <Dependency Name="System.IO.Packaging" Version="5.0.0-preview.6.20277.12" 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.6.20279.2</MicrosoftDotNetWpfDncEngVersion>
+    <MicrosoftDotNetWpfDncEngVersion>5.0.0-preview.6.20280.2</MicrosoftDotNetWpfDncEngVersion>
   </PropertyGroup>
 </Project>