Support zip file attachments with email assist

When our customers kick off their implementations, we send them an email with the kickoff deck and a zip file of project workbooks attached. We would like to semi-automate this with email assist (by surfacing a template in a CTA task so that the end user only has to check the email, attach the files relevant to the customer, and send), however we are limited by the fact that we cannot attach zip files to emails in email assist because the .zip filetype is not supported.