Editable project location

[weetster]

When using Poetry for building virtual environments, all package entries have a "location" key with a file path in the pip list output. This results in pip-api determining that all packages are editable, which is incorrect. As of pip version 21.3, an editable_project_location key is available, which is a better indicator of whether a package is truly editable. I've added support to pip-api for using this key, which should provide more accurate information for virtual environments, especially ones created with Poetry.

Thanks in advance for your review.

[di]

Thanks! If you have an interesting use case for pip-api and wouldn't mind adding it here, I'd appreciate it!

[weetster]

Thank you for merging my changes and doing a release! I'm not using pip-api directly (only through pip-audit), so I don't have anything to add to use cases.