Tradinghours

This update completely overhauls the backend of the package:
* Instead of using two storages (files and sql), it uses sqlite by default but can be used with a sql connection string to a remote database.
* The interface is mostly the same, except that some functionality, outputs, and exceptions have been added or modified.
* It is best to consult the README.md and dev-readme.md as if it's the first time you are working with this package.

Breaking Changes:
* renamed Market.generate_schedules to Market.generate_phases
* moved Schedule.list_all to Market.list_schedules
* environment variables now take precedence over the .ini file

Other Changes:
* updated test_release.yml for non-dev dependency test
* updated release.yml to include summary from release_log.txt
* added release_log.txt
* added dev-readme.md, showing set up for dev environment and CI/CD

Changes:
* add missing dependency to pyproject.toml

Breaking Changes:
* imports changed, see readme examples.

Other Changes:
* replace pytz with zoneinfo
* added automated check for tzdata version
* complete migration to pytest
* add tests for API access levels
* added workflows for releasing