1. Move dependencies for running notebooks into monorepo poetry test
deps;
2. Add script to update cassettes for a single notebook;
3. Add cassettes for some how-to guides.
---
To update cassettes for a single notebook, run
`docs/scripts/update_cassettes.sh`. For example:
```
./docs/scripts/update_cassettes.sh docs/docs/how_to/binding.ipynb
```
Requires:
1. monorepo dev and test dependencies installed;
2. env vars required by notebook are set.
Note: How-to guides are not currently run in [scheduled
job](https://github.com/langchain-ai/langchain/actions/workflows/run_notebooks.yml).
Will add cassettes for more how-to guides in subsequent PRs before
adding them to scheduled job.
