MAINT: add support for wheel DL proxy (#14010)
MAINT: add support for wheel DL proxy (#14010)

Add support for downloading SciPy wheels from behind
a proxy during the release process, falling back to
the original behavior if a common proxy-related environment
variable is not defined

This should only affect the release manager--prevents me
from having to make this change manually each time
perimosocordiae/scipy,zerothi/scipy,endolith/scipy,WarrenWeckesser/scipy,andyfaff/scipy,scipy/scipy,endolith/scipy,mdhaber/scipy,matthew-brett/scipy,perimosocordiae/scipy,mdhaber/scipy,rgommers/scipy,ilayn/scipy,matthew-brett/scipy,WarrenWeckesser/scipy,Stefan-Endres/scipy,WarrenWeckesser/scipy,zerothi/scipy,matthew-brett/scipy,ilayn/scipy,grlee77/scipy,tylerjereddy/scipy,perimosocordiae/scipy,zerothi/scipy,grlee77/scipy,andyfaff/scipy,andyfaff/scipy,Eric89GXL/scipy,endolith/scipy,e-q/scipy,tylerjereddy/scipy,rgommers/scipy,scipy/scipy,mdhaber/scipy,perimosocordiae/scipy,vigna/scipy,mdhaber/scipy,e-q/scipy,WarrenWeckesser/scipy,grlee77/scipy,Eric89GXL/scipy,vigna/scipy,Stefan-Endres/scipy,perimosocordiae/scipy,e-q/scipy,rgommers/scipy,grlee77/scipy,mdhaber/scipy,scipy/scipy,grlee77/scipy,anntzer/scipy,andyfaff/scipy,scipy/scipy,tylerjereddy/scipy,mdhaber/scipy,andyfaff/scipy,WarrenWeckesser/scipy,Stefan-Endres/scipy,ilayn/scipy,anntzer/scipy,vigna/scipy,ilayn/scipy,scipy/scipy,ilayn/scipy,andyfaff/scipy,rgommers/scipy,scipy/scipy,vigna/scipy,endolith/scipy,anntzer/scipy,Stefan-Endres/scipy,tylerjereddy/scipy,e-q/scipy,Stefan-Endres/scipy,matthew-brett/scipy,Stefan-Endres/scipy,Eric89GXL/scipy,matthew-brett/scipy,endolith/scipy,anntzer/scipy,perimosocordiae/scipy,ilayn/scipy,zerothi/scipy,WarrenWeckesser/scipy,zerothi/scipy,endolith/scipy,Eric89GXL/scipy,anntzer/scipy,zerothi/scipy,tylerjereddy/scipy,Eric89GXL/scipy,Eric89GXL/scipy,anntzer/scipy,vigna/scipy,e-q/scipy,rgommers/scipy