Also removes support for pip editable install using pyproject.toml
`pip install -e .` This was a fallback method when a requirements
file was not present, but was hacky and often failed anyway.
reckless: remove installation via pyproject.toml
This method relied on pip install in editable mode (hacky) and often
failed to complete anyhow. We should instead encourage a requirements
file to be created/used for user installation.