파이썬 버전에 따른 시간관련 함수 변경

@@ -51,8 +51,7 @@ def record() :
                 camera.stop_recording()
                 camera.stop_preview()
             
-                rec_time = time.time() - start_time
-                vid_time = rec_time.strftime("%H:%M:%S")
+                vid_time = time.strftime("%M:%S", time.gmtime(time.time()-start_time))
 
                 # s3 upload
                 '''