MAINT: use 3.8 stable in CI
MAINT: use 3.8 stable in CI

* adjust Travis CI to use Python 3.8
stable instead of 3.8-dev; also,
run the full test suite for this matrix
entry now

* adjust matplotlib version to 3.2.0rc1
to allow Python 3.8 full test suite to pass

grlee77/scipy,mdhaber/scipy,nmayorov/scipy,vigna/scipy,pizzathief/scipy,anntzer/scipy,Stefan-Endres/scipy,arokem/scipy,tylerjereddy/scipy,WarrenWeckesser/scipy,e-q/scipy,person142/scipy,endolith/scipy,endolith/scipy,pizzathief/scipy,Stefan-Endres/scipy,nmayorov/scipy,jamestwebber/scipy,anntzer/scipy,mdhaber/scipy,jamestwebber/scipy,arokem/scipy,mdhaber/scipy,ilayn/scipy,tylerjereddy/scipy,tylerjereddy/scipy,rgommers/scipy,e-q/scipy,anntzer/scipy,Eric89GXL/scipy,zerothi/scipy,anntzer/scipy,endolith/scipy,scipy/scipy,jamestwebber/scipy,mdhaber/scipy,endolith/scipy,vigna/scipy,arokem/scipy,mdhaber/scipy,Eric89GXL/scipy,andyfaff/scipy,rgommers/scipy,matthew-brett/scipy,scipy/scipy,zerothi/scipy,aeklant/scipy,vigna/scipy,zerothi/scipy,grlee77/scipy,tylerjereddy/scipy,andyfaff/scipy,e-q/scipy,grlee77/scipy,matthew-brett/scipy,ilayn/scipy,matthew-brett/scipy,grlee77/scipy,vigna/scipy,tylerjereddy/scipy,person142/scipy,perimosocordiae/scipy,Eric89GXL/scipy,ilayn/scipy,mdhaber/scipy,perimosocordiae/scipy,aeklant/scipy,rgommers/scipy,perimosocordiae/scipy,aeklant/scipy,matthew-brett/scipy,anntzer/scipy,WarrenWeckesser/scipy,jamestwebber/scipy,andyfaff/scipy,zerothi/scipy,WarrenWeckesser/scipy,aeklant/scipy,WarrenWeckesser/scipy,perimosocordiae/scipy,Stefan-Endres/scipy,ilayn/scipy,pizzathief/scipy,grlee77/scipy,matthew-brett/scipy,Stefan-Endres/scipy,pizzathief/scipy,e-q/scipy,nmayorov/scipy,aeklant/scipy,perimosocordiae/scipy,Eric89GXL/scipy,endolith/scipy,scipy/scipy,scipy/scipy,arokem/scipy,zerothi/scipy,WarrenWeckesser/scipy,jamestwebber/scipy,zerothi/scipy,endolith/scipy,Stefan-Endres/scipy,vigna/scipy,pizzathief/scipy,arokem/scipy,scipy/scipy,anntzer/scipy,person142/scipy,ilayn/scipy,Eric89GXL/scipy,rgommers/scipy,scipy/scipy,rgommers/scipy,e-q/scipy,WarrenWeckesser/scipy,Eric89GXL/scipy,perimosocordiae/scipy,Stefan-Endres/scipy,person142/scipy,nmayorov/scipy,andyfaff/scipy,nmayorov/scipy,andyfaff/scipy,ilayn/scipy,andyfaff/scipy,person142/scipy