Project-level MR approvals: Fix Change allowed approvers HTTP-method

projects.go

@@ -1329,7 +1329,7 @@ func (s *ProjectsService) ChangeAllowedApprovers(pid interface{}, opt *ChangeAll
 	}
 	u := fmt.Sprintf("projects/%s/approvers", pathEscape(project))
 
-	req, err := s.client.NewRequest("POST", u, opt, options)
+	req, err := s.client.NewRequest("PUT", u, opt, options)
 	if err != nil {
 		return nil, nil, err
 	}