nuget.config: drop internal feed

We don't need this feed, and it is causing build problems during
release.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>

Author: derrickstolee

nuget.config

@@ -2,7 +2,6 @@
 <configuration>
   <packageSources>
     <clear />
-    <add key="Dependencies" value="https://pkgs.dev.azure.com/gvfs/ci/_packaging/Dependencies/nuget/v3/index.json" />
     <add key="nuget.org" value="https://api.nuget.org/v3/index.json" />
   </packageSources>
 </configuration>