Improve DAG versioning test in Airflow 3

[tatiana]

Scenarios:

1. no changes, no new version

   • have a DAG Factory-powered DAG
   • airflow dags reserialise
   • check dag_version in the table
   • airflow dags reserialise
   • check dag_version is the same

2. changes that should not lead to DAG change, no new version

   • have a DAG Factory-powered DAG
   • airflow dags reserialise
   • make a change that should not affect the DAG version
   • check dag_version in the table
   • airflow dags reserialise
   • check dag_version is the same

3. change the dbt project, confirm there is a new version

   • have a DAG Factory-powered DAG
   • airflow dags reserialise
   • make a change that should not affect the DAG version
   • check dag_version in the table
   • airflow dags reserialise
   • check dag_version changed