Remove streaming source sleep period (ultralytics#8243)

Negatively impacts YouTube inference but removes any lag on webcams/RTSP/RTMP etc.

Resolves ultralytics#4465

utils/dataloaders.py

@@ -359,7 +359,7 @@ def update(self, i, cap, stream):
                     LOGGER.warning('WARNING: Video stream unresponsive, please check your IP camera connection.')
                     self.imgs[i] = np.zeros_like(self.imgs[i])
                     cap.open(stream)  # re-open stream if signal was lost
-            time.sleep(1 / self.fps[i])  # wait time
+            time.sleep(0.0)  # wait time
 
     def __iter__(self):
         self.count = -1