Update middleware to use cancellation token

src/Microsoft.Azure.AppConfiguration.AspNetCore/AzureAppConfigurationRefreshMiddleware.cs

@@ -26,7 +26,7 @@ public async Task InvokeAsync(HttpContext context)
         {
             foreach (var refresher in Refreshers)
             {
-                _ = refresher.TryRefreshAsync();
+                _ = refresher.TryRefreshAsync(context.RequestAborted);
             }
 
             // Call the next delegate/middleware in the pipeline