There is an `AttributeError` when `repr(querystring_parser)`

[高浩亮]

reproduce:

python: 3.8.5
python-multipart: 0.0.5

import pytest
from multipart import QuerystringParser


# pylint: disable=invalid-name
def test_repr_QuerystringParser():
    parser = QuerystringParser(callbacks={})

    with pytest.raises(AttributeError):
        repr(parser)

details about that AttributeError

self = <[AttributeError("'QuerystringParser' object has no attribute 'keep_blank_values'") raised in repr()] QuerystringParser object at 0x7f171df674f0>

    def __repr__(self):
        return "%s(keep_blank_values=%r, strict_parsing=%r, max_size=%r)" % (
            self.__class__.__name__,
>           self.keep_blank_values, self.strict_parsing, self.max_size
        )
E       AttributeError: 'QuerystringParser' object has no attribute 'keep_blank_values'

[Alex Oleshkevich]

Any plans for a new release? Current version 0.0.5 has this issue...