TypeError __init__() got an unexpected keyword argument 'username'

[fab128]

Hello
I've been using duplicity and pyrax for years for my backups to hubic.
Unfortunately, the backend seems broken since I updated to debian 11 and python3 for pyrax.

I first got the following error:

File "/usr/lib/python3/dist-packages/duplicity/backends/pyrax_identity/hubic.py", line 35, in <module>
class HubicIdentity(BaseIdentity):
NameError: name 'BaseIdentity' is not defined

Which I solved by installing duplicity (0.8.21-1) from unstable repository.

However I now get another error:
Connection failed, please check your credentials: TypeError __init__() got an unexpected keyword argument 'username'

Can you please help me with this issue ? Thanks.