Version 0.4.post1-4 of astroml is marked for autoremoval from testing on Tue 07 Jan 2020. It depends (transitively) on skimage, affected by #945389, #945393. You should try to prevent the removal by fixing these RC bugs.
Last update: 2019-12-11
Standards version of the package is outdated.
The package should be updated to follow the last version of Debian Policy
(Standards-Version 4.4.1 instead of