chore(ci) bump OpenResty version to 1.9.15.1
chore(ci) bump OpenResty version to 1.9.15.1

beauli/kong,akh00/kong,Mashape/kong,li-wl/kong,jebenexer/kong,ccyphers/kong,icyxp/kong,Kong/kong,Kong/kong,shiprabehera/kong,Kong/kong,salazar/kong,jerizm/kong,Vermeille/kong