Have diesel run migrations when rocket starts

[dennismarwood]

https://docs.rs/crate/diesel_migrations/2.0.0
https://stackoverflow.com/questions/61047355/how-to-run-diesel-migration-with-rocket-in-production
https://crates.io/crates/diesel_migrations/1.4.0

It is a bad idea to include these migrations in the dockerfile because it needs the db password passed in as a variable. I don't want to accidentally check that in. Having rocket run them at start up would fix that issue.