Audbackend

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* Changed: depend on ``audfactory>=1.0.8``
to change a critical bug
when looking for available versions of an artifact

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* Changed: check for path name before creating archive
in ``audbackend.Backend.put_archive()``

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* Added: Python 3.9 support
* Removed: Python 3.6 support

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* Added: ``verbose`` argument to
``Backend.get_archive()``,
``Backend.get_file()``,
``Backend.put_archive()``,
``Backend.put_file()``

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* Fixed: catch 403 Error for Artifactory backend paths

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* Added: ``audbackend.Backend.ls()``