adjusting browser for percy snapshot to append async to the snapshot name to note if the image is async vs default

Author: BryanSchroeder

dash/testing/browser.py

@@ -159,6 +159,11 @@ def percy_snapshot(
         """
         if widths is None:
             widths = [1280]
+        try:
+            import asgiref  # pylint: disable=unused-import, # noqa: F401
+            name += '_async'
+        except:
+            pass
 
         logger.info("taking snapshot name => %s", name)
         try: