BLD: Switch back to PyPI version of xlrd
BLD: Switch back to PyPI version of xlrd

The bug which prompted us to use our own version of xlrd is patched in
the current PyPI release, so switch back to it.

semio/zipline,gwulfs/zipline,florentchandelier/zipline,joequant/zipline,umuzungu/zipline,otmaneJai/Zipline,kmather73/zipline,zhoulingjun/zipline,Scapogo/zipline,michaeljohnbennett/zipline,dmitriz/zipline,wilsonkichoi/zipline,kmather73/zipline,euri10/zipline,cmorgan/zipline,florentchandelier/zipline,humdings/zipline,chrjxj/zipline,jordancheah/zipline,ronalcc/zipline,MonoCloud/zipline,morrisonwudi/zipline,AlirezaShahabi/zipline,wubr2000/zipline,ChinaQuants/zipline,MonoCloud/zipline,jimgoo/zipline-fork,nborggren/zipline,sketchytechky/zipline,DVegaCapital/zipline,alphaBenj/zipline,jimgoo/zipline-fork,sketchytechky/zipline,ChinaQuants/zipline,semio/zipline,zhoulingjun/zipline,dkushner/zipline,CDSFinance/zipline,alphaBenj/zipline,DVegaCapital/zipline,gwulfs/zipline,otmaneJai/Zipline,nborggren/zipline,jordancheah/zipline,YuepengGuo/zipline,YuepengGuo/zipline,quantopian/zipline,magne-max/zipline-ja,enigmampc/catalyst,grundgruen/zipline,wubr2000/zipline,umuzungu/zipline,bartosh/zipline,ronalcc/zipline,keir-rex/zipline,iamkingmaker/zipline,magne-max/zipline-ja,chrjxj/zipline,CDSFinance/zipline,wilsonkichoi/zipline,bartosh/zipline,grundgruen/zipline,humdings/zipline,michaeljohnbennett/zipline,joequant/zipline,aajtodd/zipline,AlirezaShahabi/zipline,dmitriz/zipline,Scapogo/zipline,iamkingmaker/zipline,keir-rex/zipline,enigmampc/catalyst,aajtodd/zipline,dkushner/zipline,morrisonwudi/zipline,quantopian/zipline,cmorgan/zipline,euri10/zipline