add strip parmater to String

[s3rgeym]

first_name: str = ormar.String(min_length=3, max_length=31, strip=True)
...
value = value.strip()

[SepehrBazyar]

Hi @tz4678
I think that to apply such changes, adding a parameter to the field is not an interesting method.

Since ormar uses pydantic for data validation, the examples in this link will be form pydantic's own documentation.