Update NuGet.config

NuGet.config

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <configuration>
   <packageSources>
-    <add key="AvaloniaCI" value="https://www.myget.org/F/avalonia-ci/api/v2" />
+    <add key="avalonia-all" value="https://nuget.avaloniaui.net/repository/avalonia-all/index.json" />
   </packageSources>
 </configuration>