Fix the get url

NuGet.config

@@ -5,6 +5,6 @@
     <add key="azure_app_service" value="https://www.myget.org/F/azure-appservice/api/v2" />
     <add key="azure_app_service_staging" value="https://www.myget.org/F/azure-appservice-staging/api/v2" />
     <add key="buildTools" value="https://www.myget.org/F/30de4ee06dd54956a82013fa17a3accb/" />
-    <add key="AspNetVNext" value="https://dotnet.myget.org/F/aspnetcore-dev/api/v3/index.json" />
+    <add key="AspNetVNext" value="https://www.myget.org/F/aspnetcore-dev/api/v3/index.json" />
   </packageSources>
 </configuration>