Drupal.behaviors.formSingleSubmit method name should be case-insensitive - multiple GET submissions not possilbe

Problem/Motivation

It should be possible to submit a form using the GET method twice, fe. by using target _blank.
For sure the "Prevent duplicate submissions" flag needs to be unchecked too!
Setting the form to GET via the webform UI, results in a lowercase method name 'get', which then is not respected by Drupal.behaviors.formSingleSubmit.

Proposed resolution

Use the patch from #3024953: Drupal.behaviors.formSingleSubmit method name should be case-insensitive.

The selector in Drupal.behaviors.webformRemoveFormSingleSubmit can just skip the

:not([method~="GET"])

part to catch-up the proposed core change (also already in advance).

API change

Fixed typo: Renamed Drupal.behaviors.weformRemoveFormSingleSubmit to Drupal.behaviors.webformRemoveFormSingleSubmit.