Remove TTS and convert voice feature

[alistairewj]

Adds streamlit to the pyproject.toml as it is required now

This is redundant to #62 - but I'm testing the CI to see if requiring np <2 is explicitly required (streamlit says it doesn't support np >= 2 and it's unclear if any of our other packages do)

[alistairewj]

Adding streamlit as a dependency and some experimentation exposed the following conflicts:

The conflict is caused by:
    b2aiprep 0+untagged.1.g5ba01ee depends on numpy==1.26.4
    streamlit 1.35.0 depends on numpy<2 and >=1.19.3
    transformers 4.39.3 depends on numpy>=1.17
    b2aiprep[dev,tts] 0+untagged.1.g5ba01ee depends on numpy==1.26.4
    tts 0.22.0 depends on numpy==1.22.0; python_version <= "3.10"

https://github.com/sensein/b2aiprep/actions/runs/9666011062/job/26664513604#step:4:368

After debugging, my view of the most reasonable solution was to remove the TTS package dependency. This means the CLI no longer supports converting a voice, which was a niche use anyway. The TTS package owners have recently shut down anyway: https://coqui.ai/

If we want to reimplement the feature, we probably need to use NeMo or something similar.

[DebuggerDan]

Would Torchvision still be required as a dependency? (merge commit)

Currently, when running streamlit using the README.md example & the dataset, the b2aiprep-cli program outputs torchvision is not available - cannot save figures - I am assuming this might be a remnant library initialization from the TTS & voice conversion features, but asking to be sure!

[alistairewj]

Yes AFAIK we don't use any of the features from torchvision. This is reported by one of the imports, though not sure which one in particular.