Slackbot endpoint is not responding to event_callback messages

[mlhaufe]

A 400 response is being given:

HTTP/1.1 POST http://cathedral.final-hill.com/api/slack-bot application/json 3264 - 400 106 application/json

Which means the zod schema needs to be updated. Generate a zod schema that accepts the following possibilites:

{
    "token": "Jhj5dZrVaK7ZwHHjRyZWjbDl",
    "challenge": "3eZbrw1aBm2rZgRNFdxV2595E9CY3gmdALWMmHkvFXO7tYXAYM8P",
    "type": "url_verification"
}

{
    "type": "app_mention",
    "user": "U061F7AUR",
    "text": "<@U0LAN0Z89> is it everything a river should be?",
    "ts": "1515449522.000016",
    "channel": "C123ABC456",
    "event_ts": "1515449522000016"
}

{
    "token": "ZZZZZZWSxiZZZ2yIvs3peJ",
    "team_id": "T061EG9R6",
    "api_app_id": "A0MDYCDME",
    "event": {
        "type": "app_mention",
        "user": "W021FGA1Z",
        "text": "You can count on <@U0LAN0Z89> for an honorable mention.",
        "ts": "1515449483.000108",
        "channel": "C123ABC456",
        "event_ts": "1515449483000108"
    },
    "type": "event_callback",
    "event_id": "Ev0MDYHUEL",
    "event_time": 1515449483000108,
    "authed_users": [
        "U0LAN0Z89"
    ]
}

{
    "token": "ZZZZZZWSxiZZZ2yIvs3peJ",
    "team_id": "T123ABC456",
    "api_app_id": "A123ABC456",
    "event": {
        "type": "app_mention",
        "user": "U123ABC456",
        "text": "What is the hour of the pearl, <@U0LAN0Z89>?",
        "ts": "1515449522.000016",
        "channel": "C123ABC456",
        "event_ts": "1515449522000016"
    },
    "type": "event_callback",
    "event_id": "Ev123ABC456",
    "event_time": 1515449522000016,
    "authed_users": [
        "U0LAN0Z89"
    ]
}