Check if argument is iterable. E.g. type **list** also works. (#7037)

Co-authored-by: David Burns <david.burns@theautomatedtester.co.uk>

py/selenium/webdriver/support/expected_conditions.py

@@ -245,7 +245,7 @@ def __init__(self, locator):
 
     def __call__(self, driver):
         try:
-            if isinstance(self.frame_locator, tuple):
+            if hasattr(self.frame_locator, '__iter__'):
                 driver.switch_to.frame(_find_element(driver,
                                                      self.frame_locator))
             else: