Some cameras ONVIF don't work after update to 2021.6

[ipmerlin]

The problem

Some cameras gave an unavailable error. If the camera is removed from the integration, it will not be found again. The EZVIZ camera works fine, only the Chinese cameras are missing.

What is version of Home Assistant Core has the issue?

core-2021.6.3

What was the last working version of Home Assistant Core?

core-2021.5.1

What type of installation are you running?

Home Assistant Supervised

Integration causing the issue

onvif

Link to integration documentation on our website

No response

Example YAML snippet

No response

Anything in the logs that might be useful for us?

Logger: homeassistant.config_entries
Source: util/dt.py:54
First occurred: 11:02:37 (2 occurrences)
Last logged: 11:02:40

Error setting up entry 360cam - 2e98012d2030 for onvif
Error setting up entry street360Cam1 - 9a68012d2324 for onvif
Traceback (most recent call last):
  File "/usr/src/homeassistant/homeassistant/config_entries.py", line 293, in async_setup
    result = await component.async_setup_entry(hass, self)  # type: ignore
  File "/usr/src/homeassistant/homeassistant/components/onvif/__init__.py", line 72, in async_setup_entry
    if not await device.async_setup():
  File "/usr/src/homeassistant/homeassistant/components/onvif/device.py", line 98, in async_setup
    await self.async_check_date_and_time()
  File "/usr/src/homeassistant/homeassistant/components/onvif/device.py", line 172, in async_check_date_and_time
    dt_util.get_time_zone(device_time.TimeZone)
  File "/usr/src/homeassistant/homeassistant/util/dt.py", line 54, in get_time_zone
    return cast(dt.tzinfo, zoneinfo.ZoneInfo(time_zone_str))
  File "/usr/local/lib/python3.8/site-packages/backports/zoneinfo/_tzpath.py", line 95, in find_tzfile
    _validate_tzfile_path(key)
  File "/usr/local/lib/python3.8/site-packages/backports/zoneinfo/_tzpath.py", line 108, in _validate_tzfile_path
    if os.path.isabs(path):
  File "/usr/local/lib/python3.8/posixpath.py", line 62, in isabs
    s = os.fspath(s)
TypeError: expected str, bytes or os.PathLike object, not NoneType

Additional information

No response

[probot-home-assistant]

onvif documentation
onvif source
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[probot-home-assistant]

Hey there @hunterjm, mind taking a look at this issue as its been labeled with an integration (onvif) you are listed as a codeowner for? Thanks!
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[chemelli74]

Fixed this via #51620