poetry: support for poetry metadata format 2.0

[GabMus]

[mig5]

Thank you for this! I applied this as a patch and it has solved the problem for me when running flatpak-poetry-generator.py against my poetry.lock after I upgraded poetry to version 1.5.0.

[GabMus]

I really think we should merge this

[d4nj1]

Would also be nice if the --yaml output format could be added similar to

https://github.com/flatpak/flatpak-builder-tools/blob/master/pip/flatpak-pip-generator#L55-L67 with https://github.com/flatpak/flatpak-builder-tools/blob/master/pip/flatpak-pip-generator#L480-L491

[hfiguiere]

Can you rebase this? We could get it merged eventually.

[uninstall-your-browser]

--production does not seem to work, it still tries (and fails) to retrieve dev dependencies (unless I'm somehow generating my lock file wrong?). Though it should probably be changed to --without <group-name>, since poetry has deprecated --no-dev.