CI: really move cov to py3.8
CI: really move cov to py3.8

airspeed-velocity/asv,spacetelescope/asv,airspeed-velocity/asv,spacetelescope/asv,qwhelan/asv,spacetelescope/asv,spacetelescope/asv,qwhelan/asv,airspeed-velocity/asv,qwhelan/asv,qwhelan/asv,airspeed-velocity/asv