Refactor PostgreSQL code using SQLAlchemy core

[TAnas0]

As discussed and suggested by @michaelbukachi in #25 (comment), refactor the utility PostgreSQL code to use SQLAlchemy Core.

This will avoid us security risks, make the code more readable and maintainable, and open all the features of SQLAlchemy

Please note that the PostgreSQL code is used by all of the DAGs and is critical to them, so make sure that the refactoring is compatible with the DAGs