fix: move class-level attributes to instance-level in Conversation class

[acse-efk23]

Fixes #417

Why:
Class-level attributes persisted state between sessions. Making them instance-level ensures each session starts fresh.

What:
Moved _thread, _should_stop, _conversation_id, and _last_interrupt_id from class-level to instance-level within the init method.

Note: This pull request is a proof of concept, demonstrating how moving class-level attributes to instance-level resolves the session interference issue. I understand this can’t be merged directly due to the code generation process.

[louisjoecodes]

Thank you @acse-efk23! @tudor11l, @lacop11 - do you think this is something we want to merge? Makes sense to isolate these at instance-level rather than class-level

[tudor11l]

@louisjoecodes we fixed the only one that was causing a problem which was the mutable (by not initialising it with a default value)
threading.Event = threading.Event()

I'm not a huge fan of class-level variables especially when they do not have the same value across instances. But it depends on what others think as well.

[lacop11]

Thanks @acse-efk23 !

We have fixed the mutable _should_stop issue (I didn't notice your PR earlier unfortunately, would save us some time debugging!) but I agree we need a more consistent approach.

Note that these are not class variables but instance variables, IIUC. See https://docs.python.org/3/library/typing.html#typing.ClassVar.

The problem was the mutable default value. I think we should be fine just dropping all default values and only keeping type hints on the class level, then putting all defaults into __init__. We can do it for the = None and = 0 even though they are not mutable and don't cause issues, just to be consistent and avoid accidentally adding more mutable defaults in future.

@acse-efk23 BTW:

I understand this can’t be merged directly due to the code generation process.
This particular file is not generated and is excluded in https://github.com/elevenlabs/elevenlabs-python/blob/main/.fernignore#L4 so it won't be overwritten.

If you would like to adjust the PR to keep the type hints as they were and just move the value assignment we would be happy to merge it. :)

[acse-efk23]

Thank you for the review, @lacop11 . I have updated the pull request accordingly.

[lacop11]

Looks good but the branch is out of date and conflicts, can you please rebase + resolve?

[acse-efk23]

Thank you, @lacop11 . I have rebased and solved the conflicts.

[lacop11]

Thanks, looks good!