TST: add test to io/formats/test_to_html.py to close GH6131 (#22588)
TST: add test to io/formats/test_to_html.py to close GH6131 (#22588)


jorisvandenbossche/pandas,dsm054/pandas,TomAugspurger/pandas,cython-testbed/pandas,rs2/pandas,harisbal/pandas,pandas-dev/pandas,gfyoung/pandas,toobaz/pandas,GuessWhoSamFoo/pandas,cbertinato/pandas,harisbal/pandas,datapythonista/pandas,gfyoung/pandas,cbertinato/pandas,toobaz/pandas,cython-testbed/pandas,GuessWhoSamFoo/pandas,datapythonista/pandas,gfyoung/pandas,dsm054/pandas,cbertinato/pandas,jreback/pandas,jorisvandenbossche/pandas,MJuddBooth/pandas,GuessWhoSamFoo/pandas,cbertinato/pandas,jreback/pandas,amolkahat/pandas,datapythonista/pandas,dsm054/pandas,amolkahat/pandas,toobaz/pandas,pandas-dev/pandas,pandas-dev/pandas,TomAugspurger/pandas,toobaz/pandas,dsm054/pandas,MJuddBooth/pandas,GuessWhoSamFoo/pandas,TomAugspurger/pandas,harisbal/pandas,jreback/pandas,harisbal/pandas,cython-testbed/pandas,jreback/pandas,rs2/pandas,jorisvandenbossche/pandas,dsm054/pandas,gfyoung/pandas,pandas-dev/pandas,rs2/pandas,MJuddBooth/pandas,jreback/pandas,amolkahat/pandas,amolkahat/pandas,toobaz/pandas,harisbal/pandas,datapythonista/pandas,amolkahat/pandas,MJuddBooth/pandas,GuessWhoSamFoo/pandas,cython-testbed/pandas,cython-testbed/pandas,jorisvandenbossche/pandas,rs2/pandas,gfyoung/pandas,TomAugspurger/pandas,MJuddBooth/pandas,cbertinato/pandas