pandas: Please run reference autopkgtests for mirtop/armhf and python-loompy

[Rebecca N. Palmer]

pandas 0.25.3+dfsg-3 is held in -proposed for two autopkgtest failures, 
which appear to be not its fault:

- mirtop uninstallable on armhf - the dependencies of 
python3-pandas(-lib) didn't change
- python-loompy raises on import - it also does that with the old pandas

Please run an autopkgtest without any -proposed packages to confirm this:
https://wiki.ubuntu.com/ProposedMigration#How_to_run_autopkgtests_of_a_package_against_the_version_in_the_release_pocket