CI: use numpy 1.19.5 in macOS CI
CI: use numpy 1.19.5 in macOS CI

Should get rid the failures with numpy 1.20.0, which started
picking up Accelerate. Needs to be investigated, but first
need to get CI back to a reasonable state.

endolith/scipy,perimosocordiae/scipy,andyfaff/scipy,rgommers/scipy,zerothi/scipy,Eric89GXL/scipy,e-q/scipy,perimosocordiae/scipy,e-q/scipy,anntzer/scipy,Eric89GXL/scipy,perimosocordiae/scipy,rgommers/scipy,andyfaff/scipy,Eric89GXL/scipy,vigna/scipy,grlee77/scipy,zerothi/scipy,tylerjereddy/scipy,mdhaber/scipy,e-q/scipy,Eric89GXL/scipy,perimosocordiae/scipy,matthew-brett/scipy,mdhaber/scipy,endolith/scipy,rgommers/scipy,tylerjereddy/scipy,grlee77/scipy,e-q/scipy,mdhaber/scipy,ilayn/scipy,endolith/scipy,WarrenWeckesser/scipy,WarrenWeckesser/scipy,ilayn/scipy,anntzer/scipy,e-q/scipy,perimosocordiae/scipy,matthew-brett/scipy,ilayn/scipy,Stefan-Endres/scipy,anntzer/scipy,Eric89GXL/scipy,anntzer/scipy,vigna/scipy,Stefan-Endres/scipy,WarrenWeckesser/scipy,tylerjereddy/scipy,mdhaber/scipy,andyfaff/scipy,vigna/scipy,ilayn/scipy,scipy/scipy,mdhaber/scipy,WarrenWeckesser/scipy,andyfaff/scipy,perimosocordiae/scipy,Stefan-Endres/scipy,Eric89GXL/scipy,mdhaber/scipy,grlee77/scipy,Stefan-Endres/scipy,tylerjereddy/scipy,matthew-brett/scipy,rgommers/scipy,scipy/scipy,matthew-brett/scipy,grlee77/scipy,zerothi/scipy,ilayn/scipy,rgommers/scipy,zerothi/scipy,vigna/scipy,Stefan-Endres/scipy,ilayn/scipy,andyfaff/scipy,WarrenWeckesser/scipy,matthew-brett/scipy,endolith/scipy,anntzer/scipy,tylerjereddy/scipy,vigna/scipy,grlee77/scipy,scipy/scipy,scipy/scipy,zerothi/scipy,andyfaff/scipy,zerothi/scipy,anntzer/scipy,Stefan-Endres/scipy,scipy/scipy,scipy/scipy,endolith/scipy,WarrenWeckesser/scipy,endolith/scipy