fix response `content-type` is not set if access without access token

Kairlec

2023-05-15 ca103731c721aae3f5f622e58c679ed5c09fd9e9

 src/main/java/com/genersoft/iot/vmp/vmanager/gb28181/SseController/SseController.java

@@ -17,7 +17,7 @@
 * @data: 2021-01-20
 */
@Tag(name  = "SSE推送")
@CrossOrigin

@Controller
@RequestMapping("/api")
public class SseController {