from google.transit import gtfs_realtime_pb2
import requests

feed = gtfs_realtime_pb2.FeedMessage()
response = requests.get('https://www.ztm.poznan.pl/pl/dla-deweloperow/getGtfsRtFile?file=trip_updates.pb')
feed.ParseFromString(response.content)
for entity in feed.entity:
  if entity.HasField('trip_update'):
    print(entity.trip_update)