feat(isMobilePhone): add Botswana en-BW locale

Added new condition for Botswana

New regex for Botswana numbers

Phone number information was found from the following sources:
- https://www.howtocallabroad.com/botswana/
- https://countrycode.org/botswana

Updated README.md to include en-BW

Included the new case for Botswana (en-BW)

Added test cases for isMobilePhone en-BW

Added some test cases to check length for the phone number & area code pattern.

Changed regex for BW

Fixed the pattern for Botswana mobile phone numbers and edited the test cases. I followed the convention from Table 8 of the national numbering plan document and the mobile number pattern on the Wiki page.

Update validators.js

Oops! Looks like the file didn't update with some of my modified test cases - my apologies!

src/lib/isMobilePhone.js

@@ -57,6 +57,7 @@ const phones = {
   'en-ZA': /^(\+?27|0)\d{9}$/,
   'en-ZM': /^(\+?26)?09[567]\d{7}$/,
   'en-ZW': /^(\+263)[0-9]{9}$/,
+  'en-BW': /^(\+?267)?(7[1-8]{1})\d{6}$/,
   'es-AR': /^\+?549(11|[2368]\d)\d{8}$/,
   'es-BO': /^(\+?591)?(6|7)\d{7}$/,
   'es-CO': /^(\+?57)?3(0(0|1|2|4|5)|1\d|2[0-4]|5(0|1))\d{7}$/,

test/validators.js

@@ -8215,6 +8215,31 @@ describe('Validators', () => {
           '23274560591 ',
         ],
       },
+      {
+        locale: 'en-BW',
+        valid: [
+          '+26772868545',
+          '+26776368790',
+          '+26774560512',
+          '26774560591',
+          '26778560512',
+          '74560512',
+          '76710284',
+        ],
+        invalid: [
+          '0799375902',
+          '12345',
+          '+2670745605448',
+          '2670745605482',
+          '+26779685451',
+          '+26770685451',
+          '267074560',
+          '2670ab5608',
+          '+267074560',
+          '70560512',
+          '79710284',
+        ],
+      },
       {
         locale: 'az-AZ',
         valid: [