fix: set default voice language from args if not provided

[preynal]

when passing the voice-language arg from .aider.conf or an env variable it wasn't being used and is always set to None, so the whisper model would translate a voice with an accent to it's original language

[paul-gauthier]

Thanks for your interest in aider and for filing this PR. Good catch on this bug. I fixed it a different way.

The change is available in the main branch. You can get it by installing the latest version from github:

aider --install-main-branch

# or...

python -m pip install --upgrade --upgrade-strategy only-if-needed git+https://github.com/Aider-AI/aider.git

If you have a chance to try it, let me know if it works better for you.