Move DB from postgres to sqlite

[luizirber]

Main reason: so it is easier to use the metadata in the DB for downstream analysis, especially updating a local copy of the wort signatures (without calling S3 list operations, which are SLOW when you have 6.7M objects) and generating manifests for updating branchwater.

And there aren't that many DB operations to require postgres anyway...

Useful links:

• https://github.com/bruin-data/ingestr to export data from postgres
• Optimizing SQLite for servers