CI: update triggers on PRs for wheel build action
CI: update triggers on PRs for wheel build action

This updates the PR trigger config to be the same as on other
actions. Will hopefully make a difference for spurious notifications
(see xref gh-16970) and is a good thing anyway.

[wheel build]

[skip azp] [skip circle]

mdhaber/scipy,andyfaff/scipy,endolith/scipy,andyfaff/scipy,mdhaber/scipy,scipy/scipy,mdhaber/scipy,ilayn/scipy,rgommers/scipy,anntzer/scipy,ilayn/scipy,WarrenWeckesser/scipy,mdhaber/scipy,scipy/scipy,WarrenWeckesser/scipy,rgommers/scipy,rgommers/scipy,anntzer/scipy,anntzer/scipy,Stefan-Endres/scipy,Stefan-Endres/scipy,Stefan-Endres/scipy,endolith/scipy,endolith/scipy,anntzer/scipy,Stefan-Endres/scipy,WarrenWeckesser/scipy,rgommers/scipy,WarrenWeckesser/scipy,endolith/scipy,mdhaber/scipy,rgommers/scipy,andyfaff/scipy,ilayn/scipy,anntzer/scipy,Stefan-Endres/scipy,ilayn/scipy,andyfaff/scipy,andyfaff/scipy,scipy/scipy,scipy/scipy,endolith/scipy,endolith/scipy,anntzer/scipy,scipy/scipy,andyfaff/scipy,ilayn/scipy,WarrenWeckesser/scipy,WarrenWeckesser/scipy,mdhaber/scipy,ilayn/scipy,scipy/scipy,Stefan-Endres/scipy