Fix flake8 version to 3.4.1
Fix flake8 version to 3.4.1

rocky4570/moto,dbfr3qs/moto,Brett55/moto,botify-labs/moto,ZuluPro/moto,spulec/moto,ZuluPro/moto,whummer/moto,okomestudio/moto,Affirm/moto,whummer/moto,dbfr3qs/moto,Affirm/moto,spulec/moto,okomestudio/moto,spulec/moto,rocky4570/moto,Brett55/moto,dbfr3qs/moto,okomestudio/moto,okomestudio/moto,whummer/moto,okomestudio/moto,dbfr3qs/moto,william-richard/moto,ZuluPro/moto,william-richard/moto,ZuluPro/moto,botify-labs/moto,botify-labs/moto,Affirm/moto,okomestudio/moto,rocky4570/moto,Brett55/moto,dbfr3qs/moto,ZuluPro/moto,whummer/moto,Brett55/moto,william-richard/moto,rocky4570/moto,whummer/moto,Brett55/moto,dbfr3qs/moto,Brett55/moto,spulec/moto,Affirm/moto,botify-labs/moto,botify-labs/moto,william-richard/moto,rocky4570/moto,Affirm/moto,whummer/moto,rocky4570/moto,spulec/moto,william-richard/moto,ZuluPro/moto,Affirm/moto,botify-labs/moto,spulec/moto,william-richard/moto