fix: Clear up DOM warnings

[skvale]

Description

Warning: Failed prop type: The prop `innerRef` is marked as required in `Popper`, but its value is `undefined`.
    in Popper (created by FormValidationOverlay)
    in FormValidationOverlay (created by InputGroup)

Warning: React does not recognize the `validationState` prop on a DOM element. If you intentionally want it to appear in the DOM as a custom attribute, spell it as lowercase `validationstate` instead. If you accidentally passed it from a parent component, remove it from the DOM element.
    in span (created by InputGroup.Addon)
    in InputGroup.Addon (created by DatePicker)

Warning: Received `false` for a non-boolean attribute `x-out-of-boundaries`.

If you want to write it to the DOM, pass a string instead: x-out-of-boundaries="false" or x-out-of-boundaries={value.toString()}.

If you used to conditionally omit it with x-out-of-boundaries={condition && value}, pass x-out-of-boundaries={condition ? value : undefined} instead.
    in div (created by Popper)
    in Popper (created by Popper)

Warning: React does not recognize the `showToday` prop on a DOM element. If you intentionally want it to appear in the DOM as a custom attribute, spell it as lowercase `showtoday` instead. If you accidentally passed it from a parent component, remove it from the DOM element.
    in div (created by Calendar)
    in Calendar (created by DatePicker)

fixes #issueid

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[jbadan]

Can we just child?.type?.displayName === InputGroupAddon.displayName

[jizusun]

Hi @skvale

I'm wondering why this happens

Warning: React does not recognize the `validationState` prop on a DOM element. 
If you intentionally want it to appear in the DOM as a custom attribute, spell it as lowercase `validationstate` instead. 
If you accidentally passed it from a parent component, remove it from the DOM element.

And why does this PR fixes this.

Can you briefly explain it?
Thanks so much ❤️