Automated DB migration testing

[MaddyUnderStars]

• Should run only when an entity is changed, added or removed
• Should migrate from previous commit to current for every supported DBMS

Probably going to be a pain if we try to spin up multiple entire dbms using gh actions, but hey, idk

[hbjydev]

You can do this somewhat easily actually.

https://docs.github.com/en/actions/using-containerized-services/about-service-containers