Fix case when a stream has traces with different sampling rates
Sentry Issue: WAVEQC-14
Exception: Can't merge traces with same ids but differing sampling rates!
File "waveqc/tasks.py", line 206, in check_item
result = check_removable_response(stream, channel, network, station, count)
File "waveqc/tasks.py", line 164, in check_removable_response
stream.merge(fill_value=0)