opencv low resolution with camera

Thank you so much for providing opencv package :heart:. This means a lot to me as I have been [requesting it](https://github.com/holzschu/a-shell/issues/309) for almost 2 years.

When I started to use it, I am glad to see that it can actually access the front and back camera of my iOS device (after providing permission of course).
```python
import cv2
cap = cv2.VideoCapture(0) # 0 and 1 for back and front camera
ret, frame = cap.read()
cv2.imwrite("test.jpg", frame) # save the frame from camera to file
cap.release()
```

However, the captured image only has 480x360 resolution, and there is apparently no way to change it.
I have tried the following command with no success
```python
cap.set(cv.CV_CAP_PROP_FRAME_WIDTH, 1920)
cap.set(cv.CV_CAP_PROP_FRAME_HEIGHT, 1080)
```

This could be an issue of opencv package itself, as I found the following [similar](https://stackoverflow.com/questions/12246776/ios-change-the-resolution-when-capturing-an-image-with-opencv-using-cvsetcaptur) [issues](https://github.com/opencv/opencv/issues/21196).
It's appreciated if someone can take a look on this.