also add bintrees to requirements file [skip ci]
also add bintrees to requirements file [skip ci]

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