Description

Issue #15788 arose because our minimum required erfa was not quite correct. This was not caught because in tox.ini, we have set our oldestdeps to things like pyerfa==2.0.*, which means bug-fix releases are included. Conceptually, this seems wrong: oldestdeps should test with with exactly the absolute minimum version that is allowed by our requirements. If that means that something doesn't work because of a bug, logically our minimum requirements should be updated as well.

Question: does this make sense? Should we update tox.ini and pyproject.toml with version numbers that include bug-fix micro?