fix(types): PropsWithChildren not compatible with React 17

[binhpv]

Context

The newest version of react-day-picker is not compatible with @types/react 17.

Analysis

In the last version of the library some props were declare with PropsWithChildren. This interface originally in @types/react 17 is:

    type PropsWithChildren<P> = P & { children?: ReactNode | undefined };

but in @types/react version 18 it has changed to

    type PropsWithChildren<P = unknown> = P & { children?: ReactNode | undefined };

Please note the new default of unknown. This mean new typing relies on @types/react@18 doesn't have to provide the typing when using PropsWithChildren, however it is a must with @types/react@17. The usage of PropsWithChildren in react-day-picker without the argument for the generic type make it incompatible with projects using React 17.

Solution

When using PropsWithChildren, always include argument for the generic typing so that it's also compatible with React 17 codebase.
In this PR I also change some places where the prop is declare as equal to PropsWithChildren (e.g. MonthsProps) to explicitly type as { children: ReactNode }. This ensure that children is required, and there is no need to rely on PropsWithChildren since there is no additional prop.

[gpbl]

Thanks so much @binhpv! I completely missed that. Publishing soon on npm...

[binhpv]

Thanks @gpbl for your quick follow up. Cheers!