Publish to PyPI

This is pending on https://github.com/pypa/pypi-support/issues/1124

For users that stumble upon this issue, please install it from source, as any normal python package:

```bash
git clone https://github.com/ginkgobioworks/geckopy
cd geckopy
pip install .
# to also install pytfa (optional dep for thermodynamics integration)
pip install ".[pytfa]"
```