Use Buster container images for Python 3.8
Use Buster container images for Python 3.8

william-richard/moto,spulec/moto,william-richard/moto,william-richard/moto,spulec/moto,spulec/moto,spulec/moto,william-richard/moto,spulec/moto,william-richard/moto,spulec/moto,william-richard/moto