add support for poetry for dependency badges like existing Pipenv badges

Shields already has 2 badges that parse Pipfile.lock to get the dependency/python version for the project. Considering the increasing popularity of [poetry](https://python-poetry.org/) (i can personally advocate for its far greater speed and features), I think it'd be cool if shields implemented similar badges for poetry's poetry.lock. It has the same type of data as pipenv but its in a TOML instead of JSON.

Poetry doesn't seem to have much documentation on the lock file itself, but just looking at one and knowing how TOML works I think it shouldn't be hard to figure it out. [Here's one of mine for an example](https://github.com/HexCodeFFF/mediaforge/blob/master/poetry.lock)

Start by examining the existing Pipenv badge implementations and the linked poetry.lock example to understand the dependency and Python-version data available in Poetry's TOML lock file. Add equivalent Poetry badge support and verify that both badge types parse representative poetry.lock data correctly.

Written by the indexing model from the issue text.