turn off E251 check

[MarcoGorelli]

example of offending code:

cdef inline int string_to_dts(
    str val,
    npy_datetimestruct* dts,
    NPY_DATETIMEUNIT* out_bestunit,
    int* out_local,
    int* out_tzoffset,
    bint want_exc,
    format: str | None = None,
    bint exact = True,
) except? -1:

this one may not be generally applicable to cython