Missing dependencies (on Ubuntu 20.04 at least)

[hubbardp]

On my Ubuntu 20.04 machine, I had to add the following dependencies to get the demo to work:
$ python -m pip install beautifulsoup4
$ python -m pip install accelerate

I also found that the versions of langchain and wandb specified in requirements.txt are not compatible, as indicated by this error message:
ValueError: The Weights & Biases Langchain integration does not support versions 0.0.187 and lower. To ensure proper functionality, please use version 0.0.188 or higher.

The simplest solution was to eliminate the small number of references to wandb:
serve.py: remove the import of wand, and the one call to initialize it
local_pipeline.py: remove import of wand

With these changes, the demo runs.