Add Mir card validation support

[TheDrunkenBear]

This PR introduces validation for Mir cards (Russian payment system) to the validators library.

Key Changes:

• Added mir() validator function with BIN checks (2200-2204)
• Ensures compliance with Luhn algorithm
• Includes length validation (16 digits standard)
• Added unit tests for valid/invalid cases

Why This Matters:

• Mir is a nationally critical payment system (used in Russia and neighboring countries)
• Required for apps processing payments in RUB
• Maintains parity with other card validators (Visa, Mastercard, Unionpay etc.)

[TheDrunkenBear]

cmd:

python -m ruff check --fix .