Consider using [0-9] pattern for TimePicker component

[evansjohnson]

Splitting out from #3434 (comment)

The keyboard for a TimePicker component was updated to a full numeric keyboard in #6568 by adding a type="number" prop to the input element.

From a linked GOV.UK article in the original issue there was a suggestion to use type="text" inputmode="numeric" pattern="[0-9]*". While the accessibility concerns reported there for type="number" seem to no longer apply, the TimePicker component may still benefit from the [0-9]* pattern since other characters should not be relevant.