Remove unnecessary reference to NuGet 2.8.3

Author: sharwell

.nuget/packages.config

@@ -1,7 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
   <package id="Codecov" version="1.0.1" />
-  <package id="NuGet.CommandLine" version="2.8.3" />
   <package id="OpenCover" version="4.6.247-rc" />
   <package id="ReportGenerator" version="2.3.5.0" targetFramework="net452" />
   <package id="xunit.runner.console" version="2.1.0" targetFramework="net452" />