support creating go apiview in pipeline (#3878)

* support creating go apiview in pipeline

* format

src/dotnet/APIView/APIViewWeb/Controllers/PullRequestController.cs

@@ -15,7 +15,7 @@ public class PullRequestController : Controller
         private readonly PullRequestManager _pullRequestManager;
         private readonly ILogger _logger;
 
-        string[] VALID_EXTENSIONS = new string[] { ".whl", ".api.json", ".nupkg", "-sources.jar" };
+        string[] VALID_EXTENSIONS = new string[] { ".whl", ".api.json", ".nupkg", "-sources.jar", ".gosource" };
 
         public PullRequestController(PullRequestManager pullRequestManager, ILogger<AutoReviewController> logger)
         {