Fix type in Node init args (#1115) (#1122)

Signed-off-by: Russ Webber <russ.webber@greenroomrobotics.com>
(cherry picked from commit 01a96e1)

Co-authored-by: Russ <russ@rw.id.au>

rclpy/rclpy/node.py

@@ -125,7 +125,7 @@ def __init__(
         use_global_arguments: bool = True,
         enable_rosout: bool = True,
         start_parameter_services: bool = True,
-        parameter_overrides: List[Parameter] = None,
+        parameter_overrides: Optional[List[Parameter]] = None,
         allow_undeclared_parameters: bool = False,
         automatically_declare_parameters_from_overrides: bool = False,
         enable_logger_service: bool = False