Depend on audbackend>=2.0.0

[hagenw]

Updates the code to use the new API of audbackend 2.0.0.

In addition, it fixes the setting of audb shared cache root in tests/conftests.py.
There we used

audb.config.SHARED_CACHE = cache

instead of the correct

audb.config.SHARED_CACHE_ROOT = cache

[ChristianGeng]

This MR adapts the audbcards package to use more recent audbackend releases.
In addition it fixes an issue with cache handling in the tests.

Tests are all green. I have some problems that are starting to arise with newer pathlib / Python versions.

As we cannot solve this issue, I will approve. I have pasted the error log below, just to keep it in mind.

ImportError while loading conftest '/home/cgeng@audeering.local/work/tools-public/audbcards/tests/conftest.py'.
tests/conftest.py:8: in <module>
    import audb
../../.envs/audbcards/lib/python3.12/site-packages/audb/__init__.py:1: in <module>
    from audb import info
../../.envs/audbcards/lib/python3.12/site-packages/audb/info/__init__.py:1: in <module>
    from audb.core.info import attachments
../../.envs/audbcards/lib/python3.12/site-packages/audb/core/info.py:8: in <module>
    from audb.core.api import dependencies
../../.envs/audbcards/lib/python3.12/site-packages/audb/core/api.py:7: in <module>
    import audbackend
../../.envs/audbcards/lib/python3.12/site-packages/audbackend/__init__.py:1: in <module>
    from audbackend import backend
../../.envs/audbcards/lib/python3.12/site-packages/audbackend/backend/__init__.py:6: in <module>
    from audbackend.core.backend.artifactory import Artifactory
../../.envs/audbcards/lib/python3.12/site-packages/audbackend/core/backend/artifactory.py:4: in <module>
    import artifactory
../../.envs/audbcards/lib/python3.12/site-packages/artifactory.py:425: in <module>
    class _ArtifactoryFlavour(pathlib._Flavour):
E   AttributeError: module 'pathlib' has no attribute '_Flavour'
make: *** [Makefile:54: test] Error 4

[hagenw]

The error you see is not directly related to Pathlib, but to this issue in the artifactory package: devopshq/artifactory#430.

That's also the reason why we cannot officially support Python 3.12 in audbackend, audb, here, and in a few other packages.