fix object_detection.py

[rafaelgrecco]

Fix this issue: Traceback (most recent call last):#################################################################################### | File "detector_mine.py", line 35, in bbox, label, conf = cv.detect_common_objects(rect_img, confidence=0.75, enable_gpu=True') File "/home/user/.local/lib/python3.8/site-packages/cvlib/object_detection.py", line 135, in detect_common_objects outs = net.forward(get_output_layers(net)) File "/home/user/.local/lib/python3.8/site-packages/cvlib/object_detection.py", line 29, in get_output_layers output_layers = [layer_names[i[0] - 1] for i in net.getUnconnectedOutLayers()] File "/home/user/.local/lib/python3.8/site-packages/cvlib/object_detection.py", line 29, in output_layers = [layer_names[i[0] - 1] for i in net.getUnconnectedOutLayers()] IndexError: invalid index to scalar variable.