Fix azure pipeline build fail on windows (simplcommerce#923)

For more info: https://developercommunity.visualstudio.com/content/problem/983843/dotnet-build-task-does-not-use-nugetorg-for-one-pr.html

Author: thiennn

azure-pipelines.yml

@@ -65,6 +65,12 @@ jobs:
   pool:
     vmImage: 'windows-2019'
   steps:
+  - task: DotNetCoreCLI@2
+    displayName: 'Restoring code using dotnet restore'
+    inputs: 
+      command: 'restore'
+      projects: '**/*/*.csproj'
+      includeNuGetOrg: true
   - script: dotnet build ./SimplCommerce.sln
     displayName: 'dotnet build'
   - task: DotNetCoreCLI@2