Setup flake8 configuration

Created by: arnaudsjs

Description

This PR add the flake8 and sets up a test that checks the syntax of the model:

• Setup flake8 config (setup.cfg + pyproject.toml)
• Add dev dependencies to requirements.dev.txt
• Setup dependabot config
• Add test to validate the syntax of the model

Self Check:

• Attached issue to pull request
• Changelog entry
• Version number is bumped to dev version
• Code is clear and sufficiently documented
• Sufficient test cases (reproduces the bug/tests the requested feature)
• Correct, in line with design
• End user documentation is included or an issue is created for end-user documentation

Reviewer Checklist:

• Sufficient test cases (reproduces the bug/tests the requested feature)
• Code is clear and sufficiently documented
• Correct, in line with design