TST/DEP: circular dependency with `astropy-asdf` makes `lowest` graph resolution unworkable

part of #18782
reported upstream at uv as https://github.com/astral-sh/uv/issues/16844

note that bumping `asdf-astropy>=0.8` is a possible workaround, but as noted in the upstream issue, I believe this is a fragile hack rather than a solution.