see https://docs.gitlab.com/15.0/ee/ci/yaml/artifacts_reports.html#artifactsreportscobertura-removed

This is supported in Sphinx >= 4.0. If it's missing, then Sphinx
raises a deprecation warning.

Fixes #34.

For consistency with options of bayestar-realize-coincs.

This reverts commit bfacaff5.

The ufunc testing features were added to pytest-doctestplus in
version 0.12.0.

No idea why this was failing in the tests. Maybe something shifted
subtly in matplotlib 3.5.1 released on 2021-12-21, or in astropy
released 2022-01-26?

pytest-doctest-ufunc does not yet support it.

See https://github.com/lpsinger/pytest-doctest-ufunc/pull/3.

Numpy 1.22.1 should fix the Astropy table aggregation issue.