Poetry-dotenv-plugin

Added

* Option to not override existing env variables ([16](https://github.com/mpeteuil/poetry-dotenv-plugin/pull/16))

Changed

* Switch to Poetry groups from deprecated dev section in pyproject.toml ([98413f1](https://github.com/mpeteuil/poetry-dotenv-plugin/commit/98413f1356c1ccc5e72a129cdef04cc67eb520a8))

Internal

* Upgrade Python & Poetry in the release GitHub Action ([17](https://github.com/mpeteuil/poetry-dotenv-plugin/pull/17))

This is a pre-release that serves as a proving ground.