[10.0] Switch to PSR-17 and PSR-18#511

Merged

GrahamCampbell merged 3 commits intoGitLabPHP:masterfrom

GrahamCampbell:psr18

Jul 3, 2020

Commits on Jun 28, 2020

Switch to PSR18 client impl
GrahamCampbell
committed

Commits on Jul 2, 2020