Support for nonce attribute for inline style tags

[bcalou]

Hi and thanks for this great library :)
Would you welcome a PR adding support for the nonce attribute ?
This would allow to use Content-Security-Policy headers (see https://content-security-policy.com/unsafe-inline/). Currently we have to add the unsafe-inline header, which is considered, well, unsafe ;)

Something like that:

<DayPicker
    nonce="..."

The nonce value would then be added to the inline style tag.

[gpbl]

Thanks, working on this in #1834.