scipy functions in accelsearch don't support float128

[matteobachetti]

Description of the Bug

Report by @giallix: when feeding _create_responses with z values that are float128, the function crashes with

File "(...)accelsearch.py", line 118, in _create_responses
    [SZs, CZs] = special.fresnel(Zks)
                 ^^^^^^^^^^^^^^^^^^^^
TypeError: ufunc 'fresnel' not supported for the input types, and the inputs could not be safely coerced to any supported types according to the casting rule ''safe''

Steps/Code to Replicate the Bug

@giallix provided a data file to confirm

Expected Results

No crash

Actual Results

Crash