chore: change default db pwd to ensure string type

Makefile

README.md

config/sample.engine.docker.yaml

config/sample.engine.yaml

contrib/mariadb-create-database.sql

contrib/postgresql-create-database.sql

sample.docker.env

src/aura_engine/base/config.py

src/aura_engine/base/logger.py

src/aura_engine/core/client.py