Update submodule mavlink to latest Sun Nov 19 12:39:21 UTC 2023

    - mavlink in PX4/Firmware (e819620): mavlink/mavlink@81524c2
    - mavlink current upstream: mavlink/mavlink@70181c4
    - Changes: mavlink/mavlink@81524c2...70181c4

    70181c42 2023-10-12 Hamish Willee - MAV_CMD_DO_SET_ROI_WPNEXT_OFFSET - set units to deg
f484eaf8 2023-10-11 Hamish Willee - Update test_and_deploy.yml - drop node 12 (#2041)
44197849 2023-10-11 tom - Cleanup of typos and inconsistencies in common.xml (#2044)
b295e70e 2023-09-28 Hamish Willee - Update ardupilotmega.xml - delete SPEED_TYPE (#2042)
e8d796a4 2023-09-27 Hamish Willee - SPEED_TYPE enum for MAV_CMD_DO_CHANGE_SPEED (#2039)
c313a2f3 2023-09-23 Asif Khan - common:  Add camera instance field to MAV_CMD_IMAGE_START/STOP_CAPTURE (#2024)
cad18c56 2023-09-20 Marcin - Add VELOCITY_LIMITS msg (#2015)