circleci: Use stable pyenv version
circleci: Use stable pyenv version

Earlier we were using the pyenv from their git master branch
because we wanted 3.5 beta releases. Now that 3.5 has been
released, we do not need it anymore. This commit lets us use
the default pyenv in circleci. This also makes builds faster.

sagark123/coala,sophiavanvalkenburg/coala,yashLadha/coala,arjunsinghy96/coala,aptrishu/coala,Asalle/coala,lonewolf07/coala,NalinG/coala,refeed/coala,MariosPanag/coala,meetmangukiya/coala,Uran198/coala,Balaji2198/coala,sudheesh001/coala,nemaniarjun/coala,ayushin78/coala,Shade5/coala,yashLadha/coala,tushar-rishav/coala,d6e/coala,dagdaggo/coala,kartikeys98/coala,refeed/coala,scottbelden/coala,NalinG/coala,damngamerz/coala,MattAllmendinger/coala,CruiseDevice/coala,incorrectusername/coala,djkonro/coala,karansingh1559/coala,lonewolf07/coala,djkonro/coala,d6e/coala,tushar-rishav/coala,NalinG/coala,stevemontana1980/coala,NalinG/coala,swatilodha/coala,damngamerz/coala,SambitAcharya/coala,jayvdb/coala,Asalle/coala,meetmangukiya/coala,ManjiriBirajdar/coala,scottbelden/coala,JohnS-01/coala,Asnelchristian/coala,SanketDG/coala,MariosPanag/coala,yashtrivedi96/coala,meetmangukiya/coala,svsn2117/coala,mr-karan/coala,CruiseDevice/coala,svsn2117/coala,RJ722/coala,sophiavanvalkenburg/coala,Shade5/coala,AbdealiJK/coala,rresol/coala,sagark123/coala,impmihai/coala,saurabhiiit/coala,SambitAcharya/coala,rimacone/testing2,djkonro/coala,stevemontana1980/coala,incorrectusername/coala,AbdealiJK/coala,coala-analyzer/coala,AbdealiJK/coala,netman92/coala,arafsheikh/coala,SanketDG/coala,Nosferatul/coala,SanketDG/coala,ManjiriBirajdar/coala,arjunsinghy96/coala,Asnelchristian/coala,yashtrivedi96/coala,Shade5/coala,rresol/coala,sils1297/coala,MariosPanag/coala,tltuan/coala,rimacone/testing2,coala/coala,impmihai/coala,aptrishu/coala,Nosferatul/coala,NalinG/coala,ayushin78/coala,AdeshAtole/coala,refeed/coala,Balaji2198/coala,tushar-rishav/coala,Nosferatul/coala,abhiroyg/coala,d6e/coala,dagdaggo/coala,damngamerz/coala,JohnS-01/coala,SambitAcharya/coala,netman92/coala,arush0311/coala,NiklasMM/coala,Uran198/coala,NiklasMM/coala,MattAllmendinger/coala,arjunsinghy96/coala,tltuan/coala,RJ722/coala,netman92/coala,Uran198/coala,mr-karan/coala,ManjiriBirajdar/coala,rresol/coala,NiklasMM/coala,coala/coala,Asalle/coala,aptrishu/coala,MattAllmendinger/coala,sils1297/coala,rimacone/testing2,impmihai/coala,arafsheikh/coala,coala/coala,sophiavanvalkenburg/coala,sudheesh001/coala,AdeshAtole/coala,abhiroyg/coala,SambitAcharya/coala,SambitAcharya/coala,vinc456/coala,ayushin78/coala,yland/coala,kartikeys98/coala,sudheesh001/coala,shreyans800755/coala,swatilodha/coala,jayvdb/coala,jayvdb/coala,SambitAcharya/coala,saurabhiiit/coala,tltuan/coala,coala-analyzer/coala,vinc456/coala,CruiseDevice/coala,NalinG/coala,karansingh1559/coala,yashLadha/coala,Asnelchristian/coala,incorrectusername/coala,SambitAcharya/coala,scottbelden/coala,NalinG/coala,swatilodha/coala,lonewolf07/coala,nemaniarjun/coala,nemaniarjun/coala,sagark123/coala,vinc456/coala,arush0311/coala,arafsheikh/coala,sils1297/coala,shreyans800755/coala,coala-analyzer/coala,dagdaggo/coala,arush0311/coala,mr-karan/coala,RJ722/coala,yland/coala,karansingh1559/coala,kartikeys98/coala,AdeshAtole/coala,stevemontana1980/coala,shreyans800755/coala,Balaji2198/coala,yland/coala,yashtrivedi96/coala,svsn2117/coala,saurabhiiit/coala,JohnS-01/coala,abhiroyg/coala