Add testing DB setup

[YaleChen299]

Adding test db set up. Very rough and duplicated code with the script. By default, this will try to

drop this is just in case that there are un-dropped db create migrate all connect

and the clean-up function will

close drop db

This depends on the .env.testing If not found, it will fall back to the default db name, which might hurt the dev db if anyone has one.

[github-actions[bot]]

coverage: 49.775% (+0.6%) from 49.203% when pulling 86f3485f873f8cca446252f74c556e02f41abed6 on test-db into 972695de87148bfcde9cc84e492eff660b705826 on main.

[RichDom2185]

Part of #27.