Added support for class names with multiple spaces

[Rajarshi07]

Error: Converting annotations for class: Computer keyboard 0%| | 0/3331 [00:00<?, ?it/s] Traceback (most recent call last): File ".\convert_annotations.py", line 63, in coords = np.asarray([float(labels[1]), float(labels[2]), float(labels[3]), float(labels[4])]) ValueError: could not convert string to float: 'keyboard'

Example label: Computer keyboard 392.32 2.5597440000000002 545.28 46.08 Fixed this error for class names with spaces in them.