Remove pattern="[0-9]*" from date inputs

[frankieroberto]

Currently the date inputs contain the pattern=[0-9]* attribute.

This was previously recommended in order to make mobile devices display the digit keyboard instead of the standard qwerty keyboard. However, inputmode="numeric" is now widely supported and a better way of achieving this.

pattern=[0-9]* causes a browser based validation message, which is not super accessible or well written. It can be turned off by adding the novalidate to the <form>, but people may forget to do this.

Given that pattern=[0-9]* is no longer included in the Date input in the NHS Design system, we should drop it from the React implementation too.

[frankieroberto]

@mikemonteith fancy doing this? 😄