post https://a.klaviyo.com/api/tags//relationships/campaigns/
Associate a tag with one or more campaigns. Any campaign cannot be associated with more than 100 tags.
Use the request body to pass in the ID(s) of the campaign(s) that will be associated with the tag.
Rate limits:
Burst: 3/s
Steady: 60/m
Scopes:
campaigns:write
tags:write