Add head_sha for ListWorkflowRunsOptions (#2703)

Fixes: #2687.

Author: alexellis

github/actions_workflow_runs.go

@@ -60,6 +60,7 @@ type ListWorkflowRunsOptions struct {
 	Event   string `url:"event,omitempty"`
 	Status  string `url:"status,omitempty"`
 	Created string `url:"created,omitempty"`
+	HeadSHA string `url:"head_sha,omitempty"`
 	ListOptions
 }