Update azure-pipelines.yml for Azure Pipelines

eng/pipelines/azure-pipelines.yml

@@ -92,7 +92,9 @@ stages:
             - task: NuGetCommand@2
               inputs:
                 command: 'restore'
-                restoreSolution: $(GraphicsControlsSln)
+                restoreSolution: '$(GraphicsControlsSln)'
+                feedsToUse: 'config'
+                nugetConfigPath: 'NuGet.config'
 
             - task: MSBuild@1
               displayName: 'Build sln'