limit flask-session version

[CarlosEpia]

Fixes #189 .
Already tested in a clean virtual env.

[CarlosEpia]

As discussed, the versions of Apache-airflow were limited like this: "apache-airflow>2.0,<=2.7.3", but Flask-session was again in its 0.6.0. The error got is this one:
File "/home/carlos/env/test-flask2/lib/python3.8/site-packages/airflow/www/app.py", line 186, in cached_app
app = create_app(config=config, testing=testing)
File "/home/carlos/env/test-flask2/lib/python3.8/site-packages/airflow/www/app.py", line 177, in create_app
init_airflow_session_interface(flask_app)
File "/home/carlos/env/test-flask2/lib/python3.8/site-packages/airflow/www/extensions/init_session.py", line 45, in init_airflow_session_interface
app.session_interface = AirflowDatabaseSessionInterface(
TypeError: init() missing 4 required positional arguments: 'sequence', 'schema', 'bind_key', and 'sid_length'
^C[2024-01-22T17:08:08.925+0100] {webserver_command.py:441} INFO - Received signal: 2. Closing gunicorn.

[nailend]

This works fine. Checked it on a clean SH run as well! Thanks