set lcbc008 flaky

Author: T4rk1n

tests/background_callback/test_basic_long_callback008.py

@@ -1,13 +1,15 @@
 import sys
 
 import pytest
+from flaky import flaky
 
 from tests.background_callback.utils import setup_background_callback_app
 
 
 @pytest.mark.skipif(
     sys.version_info < (3, 7), reason="Python 3.6 long callbacks tests hangs up"
 )
+@flaky(max_runs=3)
 def test_lcbc008_long_callbacks_error(dash_duo, manager):
     with setup_background_callback_app(manager, "app_error") as app:
         dash_duo.start_server(