post https://a.klaviyo.com/api/campaign-message-assign-template/
Creates a non-reusable version of the template and assigns it to the message.
Rate limits:
Burst: 10/s
Steady: 150/m
Scopes:
campaigns:write
Header
Creates a non-reusable version of the template and assigns it to the message.
Rate limits:
Burst: 10/s
Steady: 150/m
Scopes:
campaigns:write