run-tests: fix a crash when using the coverage options
35bf7f23b84c attempted to transition away from `distutils`, but the `packaging`
code lacks `StrictVersion`. I have no idea when `packaging.version` became
available, but I have it in python 3.6, so that should be good enough. For some
reason, the import checker thinks this is a local import, and needs help to
decide otherwise.
Alternately we could ditch the version check entirely, because `coverage` is
currently at 7.2.1, and the original check was added back in 2010.
edition = "2018"
max_width = 79
wrap_comments = true
error_on_line_overflow = true