feat : Add postal codes for Indonesia and South Asian countries (#16)

- Add Indonesia (ID): 5-digit postal codes
- Add Bangladesh (BD): 4-digit postal codes
- Add Pakistan (PK): 5-digit postal codes
- Add Sri Lanka (LK): 5-digit postal codes
- Add Nepal (NP): 5-digit postal codes

Total: 5 countries added with proper regex patterns, sample valid/invalid codes, local names, and descriptions.

Refs #1

Signed-off-by: Allen Elzayn <maedeeaew@gmail.com>

Author: 0xReLogic

src/postal_regex/data/postal_codes.json

@@ -1,5 +1,10 @@
 [
   {"country_code": "IN", "country_name": "India", "postal_code_regex": "^[1-9][0-9]{5}$", "sample_valid": "110001", "sample_invalid": "000000", "local_name": "भारत", "description": "Indian PIN codes are six digits; the first digit represents the postal zone."},
+  {"country_code": "ID", "country_name": "Indonesia", "postal_code_regex": "^[0-9]{5}$", "sample_valid": "12345", "sample_invalid": "ABCDE", "local_name": "Indonesia", "description": "Indonesian postal codes are five digits."},
+  {"country_code": "BD", "country_name": "Bangladesh", "postal_code_regex": "^[0-9]{4}$", "sample_valid": "1205", "sample_invalid": "ABCDE", "local_name": "বাংলাদেশ", "description": "Bangladeshi postal codes are four digits."},
+  {"country_code": "PK", "country_name": "Pakistan", "postal_code_regex": "^[0-9]{5}$", "sample_valid": "44000", "sample_invalid": "ABCDE", "local_name": "پاکستان", "description": "Pakistani postal codes are five digits."},
+  {"country_code": "LK", "country_name": "Sri Lanka", "postal_code_regex": "^[0-9]{5}$", "sample_valid": "00100", "sample_invalid": "ABCDE", "local_name": "ශ්‍රී ලංකාව", "description": "Sri Lankan postal codes are five digits."},
+  {"country_code": "NP", "country_name": "Nepal", "postal_code_regex": "^[0-9]{5}$", "sample_valid": "44600", "sample_invalid": "ABCDE", "local_name": "नेपाल", "description": "Nepalese postal codes are five digits."},
   {"country_code": "US", "country_name": "United States", "postal_code_regex": "^[0-9]{5}(?:-[0-9]{4})?$", "sample_valid": "12345-6789", "sample_invalid": "ABCDE", "local_name": "United States", "description": "US ZIP codes are five digits, with an optional four-digit extension after a dash."},
   {"country_code": "CA", "country_name": "Canada", "postal_code_regex": "^[A-Za-z]\\d[A-Za-z][ -]?\\d[A-Za-z]\\d$", "sample_valid": "K1A 0B1", "sample_invalid": "12345", "local_name": "Canada", "description": "Canadian postal codes alternate letters and digits in a six-character format."},
   {"country_code": "GB", "country_name": "United Kingdom", "postal_code_regex": "^(GIR 0AA|[A-Z]{1,2}\\d[A-Z\\d]? \\d[ABD-HJLNP-UW-Z]{2})$", "sample_valid": "SW1A 1AA", "sample_invalid": "12345", "local_name": "United Kingdom", "description": "UK postcodes vary in length; they include letters and digits and typically end with two letters."},