More compliant NuGet.config (#1397)

* Update NuGet.Config

* Update NuGet.Config

Author: TylerLeonhardt

NuGet.Config

@@ -1,10 +1,10 @@
-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="UTF-8"?>
 <configuration>
-  <solution>
-    <add key="disableSourceControlIntegration" value="true" />
-  </solution>
-  <packageSources>
-    <add key="omnisharp" value="https://www.myget.org/F/omnisharp/api/v3/index.json" protocolVersion="3" />
-    <add key="nuget.org" value="https://api.nuget.org/v3/index.json" protocolVersion="3" />
-  </packageSources>
+    <packageSources>
+        <clear />
+        <add key="nuget.org" value="https://api.nuget.org/v3/index.json" />
+    </packageSources>
+    <disabledPackageSources>
+        <clear />
+    </disabledPackageSources>
 </configuration>