[py] Fix type hint on chrome option method (#9840)

A list of strings is also allowed to be passed here
https://sites.google.com/a/chromium.org/chromedriver/capabilities

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

Author: fergushev

py/selenium/webdriver/chromium/options.py

@@ -121,7 +121,7 @@ def experimental_options(self) -> dict:
         """
         return self._experimental_options
 
-    def add_experimental_option(self, name: str, value: Union[str, int, dict]):
+    def add_experimental_option(self, name: str, value: Union[str, int, dict, List[str]]):
         """
         Adds an experimental option which is passed to chromium.