removed not working link from nuget config file

Author: HugoMario

modules/swagger-codegen/src/main/resources/aspnetcore/NuGet.Config

@@ -3,7 +3,6 @@
   <packageSources>
     <!--To inherit the global NuGet package sources remove the <clear/> line below -->
     <clear />
-    <add key="dotnet-core" value="https://www.myget.org/F/dotnet-core/api/v3/index.json" />
     <add key="api.nuget.org" value="https://api.nuget.org/v3/index.json" />
   </packageSources>
 </configuration>