[Removal] Remove `daterange` from `verify.py`

[Rubix982]

As the title states, the daterange filter is to be removed as per PR #68, #13. Specifically, the following excerpts,

    # Line 28-37
    # If 'min_date' or 'max_date' is in the keys
    if ("min_date" in kwargs or "max_date" in kwargs) and ("daterange" in kwargs):

        # Check if two contradicting keys have not been given
        raise ContradictingError(
            contradicts="daterange",
            contradicted="min_date/max_date",
            message="Using either or both of min_date and max_date, or use daterange, "
            "but not both at the same time",
        )

And,

    # Line 66
    "daterange"

The exception ContradictingError has no other use case mentioned or discussed in any other utilities, models, requirements, or configurations, and has not come up in the project discussion. Thus, it can be safely removed for now and for the future.

See models/exception.py for ContradictingError.

This is to be solved after PR #68 is merged.

[Rubix982]

Closed.