fix DeletePipelineSchedule always returning an error due to EOF

Gitlab API returns 204 on DELETE endpoints. Trying to read out the pipeline schedule from the delete response will always fail. This changes the DeletePipelineSchedule function to behave similar as the DeletePipelineTrigger function

pipeline_schedules.go

@@ -216,25 +216,24 @@ func (s *PipelineSchedulesService) TakeOwnershipOfPipelineSchedule(pid interface
 //
 // GitLab API docs:
 // https://docs.gitlab.com/ce/api/pipeline_schedules.html#delete-a-pipeline-schedule
-func (s *PipelineSchedulesService) DeletePipelineSchedule(pid interface{}, schedule int, options ...OptionFunc) (*PipelineSchedule, *Response, error) {
+func (s *PipelineSchedulesService) DeletePipelineSchedule(pid interface{}, schedule int, options ...OptionFunc) (*Response, error) {
 	project, err := parseID(pid)
 	if err != nil {
-		return nil, nil, err
+		return nil, err
 	}
 	u := fmt.Sprintf("projects/%s/pipeline_schedules/%d", url.QueryEscape(project), schedule)
 
 	req, err := s.client.NewRequest("DELETE", u, nil, options)
 	if err != nil {
-		return nil, nil, err
+		return nil, err
 	}
 
-	p := new(PipelineSchedule)
-	resp, err := s.client.Do(req, p)
+	req, err = s.client.NewRequest("DELETE", u, nil, options)
 	if err != nil {
-		return nil, resp, err
+		return nil, err
 	}
 
-	return p, resp, err
+	return s.client.Do(req, nil)
 }
 
 // CreatePipelineScheduleVariableOptions represents the available