fix a problem in warmUp (#1194)

Int process of warmUp，the pred is None, resulting in the error of "masks = self.sigmoid((result_proto_coef @ result_proto_masks.astype(np.float32).reshape(c, -1))).reshape(-1, mh, mw)"

yolov5/yolov5_seg_trt.py

@@ -181,6 +181,8 @@ class YoLov5TRT(object):
             result_boxes, result_scores, result_classid, result_proto_coef = self.post_process(
                 output_bbox[i * self.det_output_length: (i + 1) * self.det_output_length], batch_origin_h[i], batch_origin_w[i]
             )
+            if result_proto_coef.shape[0] == 0:
+                continue
             result_masks = self.process_mask(output_proto_mask, result_proto_coef, result_boxes, batch_origin_h[i], batch_origin_w[i])
 
             # Draw masks on  the original image