* map free-form objects to Dict[str, Any]
* support Forward Type References
Forward type references will be supported by default from Python 3.10 on only. Until then (and starting with Python 3.7), we can opt in by a __future__ import, cf. https://docs.python.org/3.9/whatsnew/3.7.html?highlight=forward#pep-563-postponed-evaluation-of-annotations
* re-created pet-store sample
* bump required Python version to 3.7 for generated FastAPI projects
* make pydantic modell classes process forward type references
