fix: use key while rendering arrays (#25902)
fix: use key while rendering arrays (#25902)

Fixes one of the items that was mentioned in #25854.

It fixes warning from React in `with-react-multi-carousel`.

zeit/next.js,flybayer/next.js,JeromeFitz/next.js,zeit/next.js,zeit/next.js,JeromeFitz/next.js,azukaru/next.js,JeromeFitz/next.js,azukaru/next.js,flybayer/next.js,JeromeFitz/next.js,flybayer/next.js,flybayer/next.js,azukaru/next.js,azukaru/next.js