Update the onboarding welcome message after recieving a "pin_added"
    event from Slack. Update timestamp for welcome message as well.

async def update_pin(**payload):
    """Update the onboarding welcome message after recieving a "pin_added"
    event from Slack. Update timestamp for welcome message as well.
    """
    data = payload["data"]
    web_client = payload["web_client"]
    channel_id = data["channel_id"]
    user_id = data["user"]

    # Get the original tutorial sent.
    onboarding_tutorial = onboarding_tutorials_sent[channel_id][user_id]

    # Mark the pin task as completed.
    onboarding_tutorial.pin_task_completed = True

    # Get the new message payload
    message = onboarding_tutorial.get_message_payload()

    # Post the updated message in Slack
    updated_message = await web_client.chat_update(**message)

    # Update the timestamp saved on the onboarding tutorial object
    onboarding_tutorial.timestamp = updated_message["ts"]