Fix annotation in selenium.webdriver.remove.webdriver (#5859)

Docstring description of the argument includes this text:

"Either a string representing URL of the remote server or
a custom remote_connection.RemoteConnection object."

stubs/selenium/selenium/webdriver/remote/webdriver.pyi

@@ -24,7 +24,7 @@ class WebDriver:
     error_handler: Any
     def __init__(
         self,
-        command_executor: str = ...,
+        command_executor: str | RemoteConnection = ...,
         desired_capabilities: Any | None = ...,
         browser_profile: Any | None = ...,
         proxy: Any | None = ...,