Add validation of input data using pydantic

[rubenpeters91]

Example baseModel:

class Appointment(BaseModel):
    APP_ID: str
    pseudo_id: str
    hoofdagenda: str
    specialty_code: str | None
    soort_consult: str | None
    afspraak_code: str
    start: float
    end: float
    gearriveerd: float
    created: float
    minutesDuration: int
    status: str
    status_code_original: str
    cancelationReason_code: str
    cancelationReason_display: str
    BIRTH_YEAR: int
    address_postalCodeNumbersNL: int
    name: str | None
    description: str | None
    name_text: str | None
    name_given1_callMe: str | None
    telecom1_value: str | None
    telecom2_value: str | None
    telecom3_value: str | None
    birthDate: float