go.mod: Bump hcsshim to v0.9.4

This tag contains some fixes for hostprocess containers, mainly around
fixing task stats which regressed from a change in v0.9.3.

https://github.com/microsoft/hcsshim/releases/tag/v0.9.4

Signed-off-by: Daniel Canter <dcanter@microsoft.com>

vendor/github.com/Microsoft/hcsshim/internal/jobobject/iocp.go

@@ -57,7 +57,7 @@ func pollIOCP(ctx context.Context, iocpHandle windows.Handle) {
 				}).Warn("failed to parse job object message")
 				continue
 			}
-			if err := msq.Write(notification); err == queue.ErrQueueClosed {
+			if err := msq.Enqueue(notification); err == queue.ErrQueueClosed {
 				// Write will only return an error when the queue is closed.
 				// The only time a queue would ever be closed is when we call `Close` on
 				// the job it belongs to which also removes it from the jobMap, so something