feat: add IBAN (International Bank Account Number) type

[toroleapinc]

Summary

Add a new IBAN type for validating International Bank Account Numbers.

Closes #10

Features

• Full MOD-97 checksum validation (ISO 7064)
• Country code validation against 70+ known IBAN country codes
• Per-country length validation
• Automatic normalization (uppercase, space removal)
• Descriptive error messages for each validation failure

Usage

from pydantic import BaseModel
from pydantic_extra_types.iban import IBAN

class BankAccount(BaseModel):
    iban: IBAN

account = BankAccount(iban='GB29 NWBK 6016 1331 9268 19')
print(account.iban)  # GB29NWBK60161331926819

Tests

Includes tests for:

• Valid IBANs from 14+ countries
• Space normalization and case normalization
• Invalid IBANs (wrong length, unknown country, bad checksum, etc.)

[yezz123]

All good, can you please fix the linting issue, and I will be happy to merge it

[toroleapinc]

@yezz123 Thanks for the approval! I'll fix the linting issue right away. Let me run the linters and push a fix.

Appreciate you taking the time to review!

[yezz123]

Hello @toroleapinc is this fixed so we can merge it and create a release 🙌🏻

[toroleapinc]

@yezz123 Just pushed the formatting fix — ruff wanted the dict expanded to one entry per line. CI should be green now. Ready to merge whenever you are!