Fix UK mobile number validation

The validation for UK mobile numbers is too restrictive on the third
digit, my own phone number begins 074 and the current validator does
not return a valid match, this loosens the restriction.

Author: unfunco

app/code/Magento/Ui/view/base/web/js/lib/validation/rules.js

@@ -235,7 +235,7 @@ define([
         ],
         'mobileUK': [
             function (value) {
-                return value.length > 9 && value.match(/^((0|\+44)7(5|6|7|8|9){1}\d{2}\s?\d{6})$/);
+                return value.length > 9 && value.match(/^((0|\+44)7\d{3}\s?\d{6})$/);
             },
             $.mage.__('Please specify a valid mobile number')
         ],

lib/web/mage/validation.js

@@ -384,7 +384,7 @@
         'mobileUK': [
             function (phoneNumber, element) {
                 return this.optional(element) || phoneNumber.length > 9 &&
-                    phoneNumber.match(/^((0|\+44)7(5|6|7|8|9){1}\d{2}\s?\d{6})$/);
+                    phoneNumber.match(/^((0|\+44)7\d{3}\s?\d{6})$/);
             },
             $.mage.__('Please specify a valid mobile number')
         ],