TST: Remove Python 3.6 CI testing.
TST: Remove Python 3.6 CI testing.

mhvk/numpy,madphysicist/numpy,numpy/numpy,mattip/numpy,endolith/numpy,rgommers/numpy,pbrod/numpy,pdebuyl/numpy,charris/numpy,mhvk/numpy,pbrod/numpy,anntzer/numpy,mhvk/numpy,anntzer/numpy,pdebuyl/numpy,simongibbons/numpy,pdebuyl/numpy,pbrod/numpy,endolith/numpy,jakirkham/numpy,simongibbons/numpy,mattip/numpy,simongibbons/numpy,madphysicist/numpy,charris/numpy,seberg/numpy,anntzer/numpy,rgommers/numpy,numpy/numpy,simongibbons/numpy,mattip/numpy,jakirkham/numpy,jakirkham/numpy,madphysicist/numpy,rgommers/numpy,rgommers/numpy,charris/numpy,jakirkham/numpy,numpy/numpy,endolith/numpy,mattip/numpy,endolith/numpy,charris/numpy,seberg/numpy,mhvk/numpy,seberg/numpy,numpy/numpy,pbrod/numpy,simongibbons/numpy,jakirkham/numpy,madphysicist/numpy,anntzer/numpy,seberg/numpy,pbrod/numpy,madphysicist/numpy,mhvk/numpy,pdebuyl/numpy