Catch ValueError in `fetch_gwosc_data`

Created by: EthanMarx

Addresses #1612 (closed).

This edge case occurs when the last url starts at the same timestamp that the span ends. This leads to this ligo.segments ValueError getting raised for calling __and__ with non overlapping Segments (My expectation would be to return an empty Segment, but I imagine theres good reason for choosing this behavior).

This addresses the problem by catching the ValueError and continuing the iteration past this url