Update TPL Dataflow to 4.9.0 (#37449)

eng/Versions.props

@@ -184,7 +184,7 @@
     <SystemRuntimeCompilerServicesUnsafeVersion>4.5.2</SystemRuntimeCompilerServicesUnsafeVersion>
     <SystemTextEncodingCodePagesVersion>4.5.1</SystemTextEncodingCodePagesVersion>
     <SystemTextEncodingExtensionsVersion>4.3.0</SystemTextEncodingExtensionsVersion>
-    <SystemThreadingTasksDataflowVersion>4.5.24</SystemThreadingTasksDataflowVersion>
+    <SystemThreadingTasksDataflowVersion>4.9.0</SystemThreadingTasksDataflowVersion>
     <!-- We need System.ValueTuple assembly version at least 4.0.3.0 on net47 to make F5 work against Dev15 - see https://github.com/dotnet/roslyn/issues/29705 -->
     <SystemValueTupleVersion>4.5.0</SystemValueTupleVersion>
     <SystemThreadingTasksExtensionsVersion>4.5.3</SystemThreadingTasksExtensionsVersion>