getScrollParent() in page mode misses `overflow: overlay` scroll container

### Describe the bug

While in page mode, the regex that searches the scroll parent (and in all honesty, the method should be more sophisticated, as it does not distinguish between horizontal scroll parent and vertical scroll parent) skips elements with `overflow: overlay`.

### Reproduction

https://github.com/Akryum/vue-virtual-scroller/blob/a6e07da79af0165a62fc6fc9bfb8ca08631b25ef/packages/vue-virtual-scroller/src/scrollparent.js#L3

### Validations

- [X] Check that there isn't [already an issue](https://github.com/Akryum/vue-virtual-scroller/issues) that reports the same bug to avoid creating a duplicate.