Bump the version of Drop.App (#14867)

Author: andriipatsula

src/Microsoft.DotNet.Arcade.Sdk/tools/DefaultVersions.props

@@ -71,7 +71,7 @@
     Default versions
   -->
   <PropertyGroup>
-    <DropAppVersion Condition="'$(DropAppVersion)' == ''">18.165.29912-buildid11693003</DropAppVersion>
+    <DropAppVersion Condition="'$(DropAppVersion)' == ''">19.239.34923-buildid28260713</DropAppVersion>
     <MicroBuildPluginsSwixBuildVersion Condition="'$(MicroBuildPluginsSwixBuildVersion)' == ''">1.0.422</MicroBuildPluginsSwixBuildVersion>
     <MicroBuildCoreVersion Condition="'$(MicroBuildCoreVersion)' == ''">0.2.0</MicroBuildCoreVersion>
     <MicrosoftDotNetIBCMergeVersion Condition="'$(MicrosoftDotNetIBCMergeVersion)' == ''">5.1.0-beta.21356.1</MicrosoftDotNetIBCMergeVersion>