Validation error parsing ProjectDetails() when field is empty

[xclotet]

When a Project has an empty field that according to its schema must belong to an Enum (e.g. accMan: Optional[AccManEnum]), due to the matching process it receives "accMan" (key) instead of the None (value) and raises this error:

driganttic/parse.py", line 118, in _refine_projectdetails
    return ProjectDetails(**res)
  File "pydantic/main.py", line 341, in pydantic.main.BaseModel.__init__
pydantic.error_wrappers.ValidationError: 1 validation error for ProjectDetails
accMan
  value is not a valid enumeration member;