fix exception notifier

[mcfiredrill]

should send exceptions to discord channel #streampusher_errors , but isnt currently

[SamRaymer]

Trying a fix with #268 using advice from https://birdie0.github.io/discord-webhooks-guide/other/slack_formatting.html#slack-formatting and other assorted google results

[mcfiredrill]

Thanks will deploy this and get back to you @SamRaymer

[SamRaymer]

(Update for recordkeeping: this change didn't work)