Camera is not calibrated automatically

Nobody has claimed this yet.

## Description
I've implemented the delegate like in the example with:
```
func visionManager(_: VisionManagerProtocol, didUpdateCamera camera: Camera) {
// dispatch to the main queue in order to sync access to `Camera` instance
DispatchQueue.main.async {
self.camera = camera
// you may track the calibration progress
print("Calibration: \(camera.calibrationProgress)")
}
}
```

but the calibrationProgress remains at 0.0 and I cannot use my `didUpdateWorldDescription` nor my `didUpdateRoadDescription` implementations

## Goal
As it says in the documentation the calibration process should be done automatically and last for 20-30secs

## Steps
- [ ] Step 1:
- Implemented `didUpdateCamera` on iphone SE with iOS 14.4.2. It just gets called once with 0.0 value

Start by reproducing the issue on an iPhone SE running iOS 14.4.2 with the VisionManagerProtocol didUpdateCamera implementation shown in the report. Observe whether calibrationProgress remains at 0.0 and whether didUpdateWorldDescription or didUpdateRoadDescription is invoked; done means calibration progresses automatically and those callbacks become usable as documented.

Written by the indexing model from the issue text.