[EPIC] Move to Postgresql

[flavio]

Currently SBOMbastic uses sqlite as a database. We want however to transition to PostgreSQL.

This EPIC tracks all the different issues that are required to move away from sqlite to PostgreSQL.

These are the issues, sorted by the order they must be processed:

• Research: investigate CloudNativePG #285
• helm: integrate PostgreSQL #287
• storage: move to PostgreSQL #288
• helm: update components required by sqlite #289
• docs: mention PostgreSQL dependency #290