resolve setuptools_scm issue where pluggy version is 0.0.0

[RonnyPfannschmidt]

i believe its related to the setuptools_scm issue about toml vs setup.cfg integration + versions, will investigate next week

Originally posted by @RonnyPfannschmidt in https://github.com/pytest-dev/pluggy/pull/312#discussion_r686059307

[tobagin]

any news on the fix for this? I'm getting that error while trying to build a flatpak