Use {passive: true} for the scroll event listener

[tchapi]

Hi,

Would it be possible to add an option (or maybe, always set it) so we could ad {passive: true} to the event listener ? This would improve performance in many cases (and improve audits with tools like Lighthouse for instance)

I'm talking about this line : https://github.com/eddiemf/vue-affix/blob/dba91fcb67fe2c34ef971ce0f67c304466bf5541/src/affix.vue#L479

Thanks !

[tchapi]