Fix postal code for The Netherlands

Postal code for NL allows for a space between the digits and the
letters.

Co-authored-by: Henrique Moody <henriquemoody@gmail.com>

library/Rules/PostalCode.php

@@ -122,7 +122,7 @@ class PostalCode extends Regex
         'NF' => "/^(\d{4})$/",
         'NG' => "/^(\d{6})$/",
         'NI' => "/^(\d{7})$/",
-        'NL' => "/^(\d{4}[A-Z]{2})$/",
+        'NL' => "/^(\d{4} ?[A-Z]{2})$/",
         'NO' => "/^(\d{4})$/",
         'NP' => "/^(\d{5})$/",
         'NZ' => "/^(\d{4})$/",

tests/unit/Rules/PostalCodeTest.php

@@ -91,6 +91,8 @@ class PostalCodeTest extends \PHPUnit_Framework_TestCase
             ['US', '02179'],
             ['YE', ''],
             ['PL', '99-300'],
+            ['NL', '1012 GX'],
+            ['NL', '1012GX'],
         ];
     }