NuGet: clear other sources

src/NuGet.config

@@ -1,9 +1,10 @@
 <?xml version="1.0" encoding="utf-8"?>
 <configuration>
-  <config>
-    <add key="repositoryPath" value="packages" />
-  </config>
   <packageSources>
-    <add key="NuGet" value="https://api.nuget.org/v3/index.json" />
+    <clear />
+    <add key="nuget.org" value="https://api.nuget.org/v3/index.json" protocolVersion="3" />
   </packageSources>
-</configuration>
+  <solution>
+    <add key="disableSourceControlIntegration" value="true" />
+  </solution>
+</configuration>