I'm alright with making the default Black version tied to the action version being used. For context version was introduced because the action didn't exist for a long time so tying black version to action version wouldn't work for version 19.10b0 for example. In hidesight, having the default being the action version keeping the version configuration option around as an escape hatch is the better solution. This will involve some complexity since commit SHAs aren't supported by the version code (but are by GHA) but there might be some pre-existing logic in scripts/diff_shades_gha_helper.py we could reuse.

Originally posted by @ichard26 in #1140 (comment)