Fix time precision issue

Fix time precision issue by getting nanosecond directly from stored
UTCDateTime instead of UTC timestamp

sohstationviewer/model/reftek/rt130_experiment/reftek.py

@@ -160,8 +160,7 @@ def convert_packet_to_obspy_format(packet: Union[EHETPacket, DTPacket], unpacker
     # Obspy only stores the last two digits of the year.
     converted_packet['year'] = packet.header.time.year % 100
     converted_packet['unit_id'] = packet.header.unit_id
-    # We need to convert the stored time from second to nanosecond
-    converted_packet['time'] = packet.header.time.timestamp * 10**9
+    converted_packet['time'] = packet.header.time.ns
     converted_packet['byte_count'] = packet.header.byte_count
     converted_packet['packet_sequence'] = packet.header.packet_sequence
     converted_packet['event_number'] = packet.extended_header.event_number