In line 134 of gwFast.signal, the following call is being made:
self.strainInteg = igt.cumtrapz(self.strainFreq[mask]**(-7./3.)/S[mask], self.strainFreq[mask], initial = 0)
scipy.integrate.cumtrapz, which was removed at version 1.14.0 (current version is 1.15.3).
release note
cumtrapz should be repalced with cumulative_trapezoid, which has been available since version 1.6.0 releate note
This drop-in replacement solved this issue for me locally.
Thank you.