Remove broken test for Panel with to_pandas() (#4028)
Remove broken test for Panel with to_pandas() (#4028)

* Remove broken test for Panel with to_pandas()

We don't support creating a Panel with to_pandas() with *any* version of
pandas at present, so this test was previous broken if pandas < 0.25 was
isntalled.

* remove unused import

* Fixup LooseVersion import
jhamman/xarray,pydata/xarray,markelg/xray,markelg/xray,xray/xray,pydata/xarray,pydata/xarray,markelg/xray,jhamman/xarray,jhamman/xarray