feat(isPostalCode): add PK locale (#2052)

* Add validation, tests for postal code locale PK

Reference for valid list of postal codes: https://www.pakpost.gov.pk/postcodes.php

* Fix: missing trailing comma results in failed tests

* Move reference link for valid postal code list

* Fix: missing comma in README.md

Author: mateeni-dev

README.md

@@ -157,7 +157,7 @@ Validator                               | Description
 **isOctal(str)**                        | check if the string is a valid octal number.
 **isPassportNumber(str, countryCode)**    | check if the string is a valid passport number.<br/><br/>`countryCode` is one of `['AM', 'AR', 'AT', 'AU', 'AZ', 'BE', 'BG', 'BY', 'BR', 'CA', 'CH', 'CN', 'CY', 'CZ', 'DE', 'DK', 'DZ', 'EE', 'ES', 'FI', 'FR', 'GB', 'GR', 'HR', 'HU', 'IE', 'IN', 'IR', 'ID', 'IS', 'IT', 'JM', 'JP', 'KR', 'KZ', 'LI', 'LT', 'LU', 'LV', 'LY', 'MT', 'MX', 'MY', 'MZ', 'NL', 'NZ', 'PH', 'PK', 'PL', 'PT', 'RO', 'RU', 'SE', 'SL', 'SK', 'TH', 'TR', 'UA', 'US', 'ZA']`.  Locale list is `validator.passportNumberLocales`.
 **isPort(str)**                         | check if the string is a valid port number.
-**isPostalCode(str, locale)**           | check if the string is a postal code.<br/><br/>`locale` is one of `['AD', 'AT', 'AU', 'AZ', 'BA', 'BE', 'BG', 'BR', 'BY', 'CA', 'CH', 'CN', 'CO', 'CZ', 'DE', 'DK', 'DO', 'DZ', 'EE', 'ES', 'FI', 'FR', 'GB', 'GR', 'HR', 'HT', 'HU', 'ID', 'IE', 'IL', 'IN', 'IR', 'IS', 'IT', 'JP', 'KE', 'KR', 'LI', 'LK', 'LT', 'LU', 'LV', 'MG', 'MT', 'MX', 'MY', 'NL', 'NO', 'NP', 'NZ', 'PL', 'PR', 'PT', 'RO', 'RU', 'SA', 'SE', 'SG', 'SI', 'SK', 'TH', 'TN', 'TW', 'UA', 'US', 'ZA', 'ZM']` OR `'any'`. If 'any' is used, function will check if any of the locales match. Locale list is `validator.isPostalCodeLocales`.
+**isPostalCode(str, locale)**           | check if the string is a postal code.<br/><br/>`locale` is one of `['AD', 'AT', 'AU', 'AZ', 'BA', 'BE', 'BG', 'BR', 'BY', 'CA', 'CH', 'CN', 'CO', 'CZ', 'DE', 'DK', 'DO', 'DZ', 'EE', 'ES', 'FI', 'FR', 'GB', 'GR', 'HR', 'HT', 'HU', 'ID', 'IE', 'IL', 'IN', 'IR', 'IS', 'IT', 'JP', 'KE', 'KR', 'LI', 'LK', 'LT', 'LU', 'LV', 'MG', 'MT', 'MX', 'MY', 'NL', 'NO', 'NP', 'NZ', 'PK', 'PL', 'PR', 'PT', 'RO', 'RU', 'SA', 'SE', 'SG', 'SI', 'SK', 'TH', 'TN', 'TW', 'UA', 'US', 'ZA', 'ZM']` OR `'any'`. If 'any' is used, function will check if any of the locales match. Locale list is `validator.isPostalCodeLocales`.
 **isRFC3339(str)**                      | check if the string is a valid [RFC 3339][RFC 3339] date.
 **isRgbColor(str [,options])**                     | check if the string is a rgb or rgba color.<br/></br>`options` is an object with the following properties<br/><br/>`includePercentValues` defaults to `true`. If you don't want to allow to set `rgb` or `rgba` values with percents, like `rgb(5%,5%,5%)`, or `rgba(90%,90%,90%,.3)`, then set it to false.<br/><br/>`allowSpaces` defaults to `true`, which prohibits whitespace. If set to false, whitespace between color values is allowed, such as `rgb(255, 255, 255)` or even `rgba(255,       128,        0,      0.7)`.
 **isSemVer(str)**                       | check if the string is a Semantic Versioning Specification (SemVer).

src/lib/isPostalCode.js

@@ -57,6 +57,8 @@ const patterns = {
   NO: fourDigit,
   NP: /^(10|21|22|32|33|34|44|45|56|57)\d{3}$|^(977)$/i,
   NZ: fourDigit,
+  // https://www.pakpost.gov.pk/postcodes.php
+  PK: fiveDigit,
   PL: /^\d{2}\-\d{3}$/,
   PR: /^00[679]\d{2}([ -]\d{4})?$/,
   PT: /^\d{4}\-\d{3}?$/,

test/validators.test.js

@@ -12658,6 +12658,22 @@ describe('Validators', () => {
           '4144',
         ],
       },
+      {
+        locale: 'PK',
+        valid: [
+          '25000',
+          '44000',
+          '54810',
+          '74200',
+        ],
+        invalid: [
+          '5400',
+          '540000',
+          'NY540',
+          '540CA',
+          '540-0',
+        ],
+      },
       {
         locale: 'MG',
         valid: [