flask create-packets errors with module 'onesignal_sdk.client' has no attribute 'Notification'

[galenguyer]

Sentry issue: https://sentry.io/organizations/csh/issues/2595998921/?project=1804454

[mxmeinhold]

This is probably my fault. I'll take a look and see if I can find it.

[mxmeinhold]

We should follow up that revert with actually updating onesignal.