onPageSelected and onScroll gives wrong position when animation wasn't completed on previous page on iPhone 12

## Environment
```
"react-native": "0.63.4",
"react": "16.14.0",
"react-native-pager-view": "^5.4.9"
```

iOS 15.2

## Description
onPageSelected and onScroll handlers giving wrong index on iPhone 12 simulator (as well as on real device too), but works on iPhone 11 (and older devices) correct. See video below (demonstrates apps on iPhone 11 and iPhone 12)

## Reproducible Demo

```

{children}

```

```
const onPageSelected = useCallback(
(e) => {
const pageIdx = e.nativeEvent.position;
console.log(pageIdx, 'PAGE IDX')
setActivePage(pageIdx);
onItemActive(pageIdx);
},
[onItemActive],
);
```

Video 1 (correct behaviour, iPhone 11 iOS 15.2, after animation is not finished onPageSelected provides correct page after gesture completed)
https://user-images.githubusercontent.com/9297785/149826584-b309417c-252e-4c55-b2c5-302dc1bb90f2.mp4

Video 2 (incorrect behaviour, iPhone 12 iOS 15.2, after animation is not finished onPageSelected provides previous page number after gesture completed)
https://user-images.githubusercontent.com/9297785/149826806-cbab3e2d-93f5-4ebf-a919-8e4b8d75f471.mp4

Comienza con el uso de PagerView y los controladores onPageSelected/onScroll mostrados en el issue, luego reproduce el deslizamiento vertical interrumpido en un iPhone 12 con iOS 15.2 y compáralo con un iPhone 11. Se considera terminado cuando el evento informa de la página de destino completada en lugar de la página anterior después de una animación sin finalizar.

Escrito por el modelo de indexación a partir del texto del issue.