Fix bool filter type to handle None values

[denisfrm]

This PR fixes the issue that find() is not able to handle None values as written in the issue #153

[michaelmior]

I would prefer not to remove the bool case that is currently handled, but otherwise this looks good.

[denisfrm]

I would prefer not to remove the bool case that is currently handled, but otherwise this looks good.

Hi @michaelmior , the problem is that the boolean type should not be converted. An example is this unit test:

    pytest.param(
        "foo[?flag = true].color",
        {
            "foo": [
                {"color": "blue", "flag": True},
                {"color": "green", "flag": 2},
                {"color": "red", "flag": "hi"},
                {"color": "gray", "flag": None},
            ]
        },
        ["blue"],
        id="boolean-filter-with-null",
    ),

When you want to search for colors only if flag is equal to true, if we convert the values ​​2, "hi". They will be converted to True. So the result of the test would be ["blue", "green", "red"] instead of ["blue"]