Update graphql term data when post meta is changed.

[vinniedauer]

Currently, if I add a pre-existing taxonomy term to a post and save the post, the graphql data for that term is not updated. In order to reflect the new connection between that post and term, I have to edit and save the term. It would be great if, when I add or remove a term from a post, that term's graphql data was updated without having to then manually edit/save the term.