[CR][ENG-6022] Hotfix: fix postcommit celery bug for spam checks

[felliott]

Purpose

Something in python-upgrade started adding complex objects to the request headers. These headers were being passed into the celery task call for spam-checking. Because the complex objects can't be serialized, the task was failing. Knock that off.

Changes

Stop adding request headers to spam check kwargs. We already set the necessary kwargs.

QA Notes

Will be dev-tested.

Documentation

None.

Side Effects

None expected.

Ticket

https://openscience.atlassian.net/browse/ENG-6022