Remove database dependencies

[hwakabh]

AsIs

With current code basis, the transaction with MySQL will be used mysql-connector-python directly, without using ORM like SQLAlchemy.
As commented, with SQLAlchemy we can integrate them with its dialects, and draft base class have been implemented in #72.

ToDo

• Complete implementations of Airport model with replacing table schema in insert.sql with ORM syntax
• Replace SQL for database with SQLAlchemy Python methods

(Optional) Acceptance Criteria

• Tests/Build pipeline will be passed
• Application runs without any error locally