remove allow_failures for python 3.x from appveyor
remove allow_failures for python 3.x from appveyor

shamangeorge/beets,diego-plan9/beets,ibmibmibm/beets,mosesfistos1/beetbox,jackwilsdon/beets,lengtche/beets,madmouser1/beets,beetbox/beets,beetbox/beets,madmouser1/beets,ibmibmibm/beets,mosesfistos1/beetbox,artemutin/beets,xsteadfastx/beets,madmouser1/beets,Kraymer/beets,Kraymer/beets,SusannaMaria/beets,madmouser1/beets,beetbox/beets,sampsyo/beets,shamangeorge/beets,Kraymer/beets,xsteadfastx/beets,Kraymer/beets,pkess/beets,MyTunesFreeMusic/privacy-policy,lengtche/beets,mosesfistos1/beetbox,artemutin/beets,lengtche/beets,shamangeorge/beets,shamangeorge/beets,sampsyo/beets,diego-plan9/beets,pkess/beets,artemutin/beets,ibmibmibm/beets,pkess/beets,jackwilsdon/beets,SusannaMaria/beets,jackwilsdon/beets,MyTunesFreeMusic/privacy-policy,artemutin/beets,diego-plan9/beets,xsteadfastx/beets,sampsyo/beets,beetbox/beets,MyTunesFreeMusic/privacy-policy,jackwilsdon/beets,SusannaMaria/beets,mosesfistos1/beetbox,xsteadfastx/beets,lengtche/beets,pkess/beets,MyTunesFreeMusic/privacy-policy,sampsyo/beets,SusannaMaria/beets,ibmibmibm/beets,diego-plan9/beets