add sleep to some dash table tests

Author: T4rk1n

components/dash-table/tests/selenium/test_derived_props.py

@@ -89,6 +89,8 @@ def test_tdrp001_select_rows(test):
     target.row(0).select()
     target.row(1).select()
 
+    time.sleep(1)
+
     assert test.find_element("#active_cell").get_attribute("innerHTML") in [
         "None",
         json.dumps([]),
@@ -413,6 +415,8 @@ def test_tdrp005_filtered_and_sorted_row_select(test):
     target.row(1).select()
     target.row(2).select()
 
+    time.sleep(1)
+
     assert test.find_element("#active_cell").get_attribute("innerHTML") in [
         "None",
         json.dumps([]),