Allow `int` for `destination` in `OutlineItem.__init__`
Allow `int` for `destination` in `OutlineItem.__init__`

The ['Outlines' docs][1] as well as the docstring for `__init__` says you can use a page number for
`destination`, which the examples in the docs does as well (e.g. `OutlineItem('Section One', 0)`).

[1]: https://pikepdf.readthedocs.io/en/latest/topics/outlines.html#destinations

pikepdf/pikepdf,pikepdf/pikepdf,pikepdf/pikepdf