core/numbers: Use floor division in a doctest
core/numbers: Use floor division in a doctest

In Python 3 true division is the default, so change a doctest to use
floor division (//). The // operator is unambiguous in all Python
versions.

Shaswat27/sympy,ChristinaZografou/sympy,chaffra/sympy,Titan-C/sympy,debugger22/sympy,souravsingh/sympy,rahuldan/sympy,mcdaniel67/sympy,atreyv/sympy,liangjiaxing/sympy,Mitchkoens/sympy,toolforger/sympy,sahilshekhawat/sympy,skidzo/sympy,kaichogami/sympy,kmacinnis/sympy,pandeyadarsh/sympy,lindsayad/sympy,ahhda/sympy,mcdaniel67/sympy,moble/sympy,postvakje/sympy,sahmed95/sympy,ChristinaZografou/sympy,abloomston/sympy,hrashk/sympy,hargup/sympy,abloomston/sympy,ga7g08/sympy,Gadal/sympy,toolforger/sympy,Sumith1896/sympy,hargup/sympy,kevalds51/sympy,cswiercz/sympy,souravsingh/sympy,wyom/sympy,aktech/sympy,amitjamadagni/sympy,postvakje/sympy,garvitr/sympy,maniteja123/sympy,beni55/sympy,jaimahajan1997/sympy,ahhda/sympy,AkademieOlympia/sympy,jamesblunt/sympy,kmacinnis/sympy,moble/sympy,Arafatk/sympy,VaibhavAgarwalVA/sympy,Gadal/sympy,asm666/sympy,AunShiLord/sympy,mafiya69/sympy,Arafatk/sympy,hargup/sympy,beni55/sympy,jbbskinny/sympy,kaichogami/sympy,ga7g08/sympy,yashsharan/sympy,mafiya69/sympy,bukzor/sympy,abhiii5459/sympy,ChristinaZografou/sympy,mcdaniel67/sympy,meghana1995/sympy,cswiercz/sympy,Davidjohnwilson/sympy,pandeyadarsh/sympy,sahilshekhawat/sympy,moble/sympy,Titan-C/sympy,jaimahajan1997/sympy,VaibhavAgarwalVA/sympy,dqnykamp/sympy,debugger22/sympy,vipulroxx/sympy,flacjacket/sympy,pbrady/sympy,jamesblunt/sympy,grevutiu-gabriel/sympy,sunny94/temp,sahmed95/sympy,sahilshekhawat/sympy,drufat/sympy,Shaswat27/sympy,AunShiLord/sympy,kumarkrishna/sympy,rahuldan/sympy,wanglongqi/sympy,dqnykamp/sympy,madan96/sympy,jerli/sympy,atreyv/sympy,meghana1995/sympy,wyom/sympy,shipci/sympy,lindsayad/sympy,lidavidm/sympy,madan96/sympy,MridulS/sympy,Designist/sympy,grevutiu-gabriel/sympy,wanglongqi/sympy,kumarkrishna/sympy,MechCoder/sympy,MridulS/sympy,kaichogami/sympy,iamutkarshtiwari/sympy,beni55/sympy,garvitr/sympy,cccfran/sympy,shikil/sympy,asm666/sympy,lidavidm/sympy,skirpichev/omg,MechCoder/sympy,ga7g08/sympy,Mitchkoens/sympy,VaibhavAgarwalVA/sympy,madan96/sympy,jaimahajan1997/sympy,emon10005/sympy,kaushik94/sympy,yukoba/sympy,srjoglekar246/sympy,maniteja123/sympy,debugger22/sympy,kaushik94/sympy,liangjiaxing/sympy,MridulS/sympy,Davidjohnwilson/sympy,MechCoder/sympy,emon10005/sympy,oliverlee/sympy,iamutkarshtiwari/sympy,saurabhjn76/sympy,vipulroxx/sympy,drufat/sympy,aktech/sympy,chaffra/sympy,cccfran/sympy,lidavidm/sympy,jbbskinny/sympy,jerli/sympy,kevalds51/sympy,Designist/sympy,kaushik94/sympy,mafiya69/sympy,grevutiu-gabriel/sympy,Curious72/sympy,bukzor/sympy,sampadsaha5/sympy,Curious72/sympy,Vishluck/sympy,Vishluck/sympy,drufat/sympy,oliverlee/sympy,skidzo/sympy,pandeyadarsh/sympy,kumarkrishna/sympy,jamesblunt/sympy,souravsingh/sympy,maniteja123/sympy,yukoba/sympy,skidzo/sympy,Designist/sympy,garvitr/sympy,saurabhjn76/sympy,shipci/sympy,Davidjohnwilson/sympy,emon10005/sympy,amitjamadagni/sympy,atreyv/sympy,lindsayad/sympy,toolforger/sympy,atsao72/sympy,abhiii5459/sympy,jbbskinny/sympy,Curious72/sympy,Sumith1896/sympy,Gadal/sympy,abhiii5459/sympy,pbrady/sympy,Shaswat27/sympy,dqnykamp/sympy,farhaanbukhsh/sympy,cswiercz/sympy,farhaanbukhsh/sympy,meghana1995/sympy,Mitchkoens/sympy,asm666/sympy,Vishluck/sympy,atsao72/sympy,ahhda/sympy,shipci/sympy,AkademieOlympia/sympy,iamutkarshtiwari/sympy,kmacinnis/sympy,Sumith1896/sympy,sampadsaha5/sympy,cccfran/sympy,chaffra/sympy,AunShiLord/sympy,sunny94/temp,Titan-C/sympy,yashsharan/sympy,yukoba/sympy,postvakje/sympy,kevalds51/sympy,farhaanbukhsh/sympy,abloomston/sympy,oliverlee/sympy,sahmed95/sympy,atsao72/sympy,shikil/sympy,rahuldan/sympy,hrashk/sympy,diofant/diofant,saurabhjn76/sympy,liangjiaxing/sympy,hrashk/sympy,pbrady/sympy,yashsharan/sympy,sunny94/temp,wanglongqi/sympy,vipulroxx/sympy,sampadsaha5/sympy,aktech/sympy,jerli/sympy,AkademieOlympia/sympy,Arafatk/sympy,wyom/sympy,shikil/sympy,bukzor/sympy