COCO.loadRes: copy the info dict to the results too

[carandraug]

The COCO.loadRes returns a new COCO object with the results. It does this by copying the images and categories fields from the COCO data object. However, it does not copy the info dict. The end result is that the info() method in the returned results COCO fails:

>>> coco_res = coco_data.loadRes(...)
>>> coco_res.info()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.11/site-packages/pycocotools/coco.py", line 124, in info
    for key, value in self.dataset['info'].items():
                      ~~~~~~~~~~~~^^^^^^^^
KeyError: 'info'

ThIs PR copies the original info field so things work. I'm not sure if it is the best choice since the results should maybe have a different "info" but there is no "info" on the results file so this seems the best option to prevent errors without changing the API.