Set readthedocs environment to python3.
Set readthedocs environment to python3.

kelle/astropy,AustereCuriosity/astropy,tbabej/astropy,AustereCuriosity/astropy,MSeifert04/astropy,dhomeier/astropy,dhomeier/astropy,lpsinger/astropy,funbaker/astropy,lpsinger/astropy,dhomeier/astropy,dhomeier/astropy,AustereCuriosity/astropy,pllim/astropy,astropy/astropy,MSeifert04/astropy,aleksandr-bakanov/astropy,larrybradley/astropy,aleksandr-bakanov/astropy,pllim/astropy,joergdietrich/astropy,pllim/astropy,tbabej/astropy,astropy/astropy,joergdietrich/astropy,MSeifert04/astropy,bsipocz/astropy,joergdietrich/astropy,StuartLittlefair/astropy,DougBurke/astropy,mhvk/astropy,astropy/astropy,joergdietrich/astropy,StuartLittlefair/astropy,larrybradley/astropy,saimn/astropy,aleksandr-bakanov/astropy,saimn/astropy,DougBurke/astropy,DougBurke/astropy,lpsinger/astropy,funbaker/astropy,StuartLittlefair/astropy,joergdietrich/astropy,stargaser/astropy,kelle/astropy,mhvk/astropy,astropy/astropy,bsipocz/astropy,pllim/astropy,mhvk/astropy,mhvk/astropy,stargaser/astropy,DougBurke/astropy,tbabej/astropy,larrybradley/astropy,tbabej/astropy,mhvk/astropy,saimn/astropy,stargaser/astropy,stargaser/astropy,kelle/astropy,StuartLittlefair/astropy,astropy/astropy,lpsinger/astropy,larrybradley/astropy,tbabej/astropy,kelle/astropy,funbaker/astropy,AustereCuriosity/astropy,saimn/astropy,pllim/astropy,AustereCuriosity/astropy,StuartLittlefair/astropy,MSeifert04/astropy,lpsinger/astropy,saimn/astropy,dhomeier/astropy,bsipocz/astropy,larrybradley/astropy,kelle/astropy,bsipocz/astropy,funbaker/astropy,aleksandr-bakanov/astropy