Proposed change

When we do not know the position of a cover (eg. after restart of HA) we now return None for is_closed() so the state resolves to "unknown".
self._device.current_position() is None on init. When the cover is moved once the state gets calculated in xknx internally - so it is always available even if no position_state_address is configured.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
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• New feature (which adds functionality to an existing integration)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
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Checklist

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