Bug#999415: transition: pandas 1.1 -> 1.3

[Rebecca N. Palmer]

The autopkgtest found 2 more, dask #1001348 (32 bit only) and 
python-anndata #1001349 (hidden in my test by an unrelated bug). 
python-skbio and python-cooler have been fixed, and I consider hyperspy 
to probably be a non-pandas-related bug (and it isn't in testing 
anyway).  I have now tested rdkit, which worked.

This leaves cfgrib, dask, joypy and python-anndata.  All except cfgrib 
have what I think are patches, though I haven't tested any of these.