Notifier crashes due to incompatible date times being compared

[fniessink]

Traceback (most recent call last):
notifier_1       |   File "/home/notifier/quality_time_notifier.py", line 112, in <module>
notifier_1       |     asyncio.run(notify(logging.INFO))  # pragma: no cover
notifier_1       |   File "/usr/local/lib/python3.9/asyncio/runners.py", line 44, in run
notifier_1       |     return loop.run_until_complete(main)
notifier_1       |   File "/usr/local/lib/python3.9/asyncio/base_events.py", line 642, in run_until_complete
notifier_1       |     return future.result()
notifier_1       |   File "/home/notifier/quality_time_notifier.py", line 43, in notify
notifier_1       |     most_recent_measurement_seen = most_recent_measurement_timestamp(json)
notifier_1       |   File "/home/notifier/quality_time_notifier.py", line 73, in most_recent_measurement_timestamp
notifier_1       |     most_recent = max(most_recent, datetime.fromisoformat(recent_measurements[-1]["end"]))
notifier_1       | TypeError: can't compare offset-naive and offset-aware datetimes