add poetry config file poetry.toml

[saurbhc]

Problem

Setting up poetry config is a manual process - Instructions here: https://github.com/v7labs/darwin-py/blob/master/docs/DEV.md#poetry

Solution

Adding poetry configurations in a Local configuration file poetry.toml to make our life easier :)

Configuration Docs:

• virtualenvs.in-project
• virtualenvs.prefer-active-python

Changelog

[dev] Move Poetry Configuration to poetry.toml

[owencjones]

Sure, doesn't seem to be a problem, might be useful. Lgtm