Validation issue with Belarusian phone numbers (Country Code: BY)

[TaSha-spec]

Describe the bug
The package intl_phone_number_input incorrectly validates Belarusian phone numbers. Currently, the library requires numbers with the country code BY to have at least 10 digits. However, valid Belarusian numbers only contain 9 digits after the country code (e.g., +375291234567).

Package version
intl_phone_number_input: ^0.7.4

Flutter version
This widget is integrated as a custom widget in Flutter Flow.

To Reproduce
Steps to reproduce the behavior:
Add the widget to your app.
Select Belarus (BY) as the country.
Input a valid number with 9 digits (e.g., +375291234567).
Observe the validation error stating the number is invalid.

Expected behavior
The number +375291234567 (9 digits) should pass validation as it is a valid Belarusian number.

Screenshots
If applicable, add screenshots to help explain your problem.

** Targeted platforms (please complete the following information):**
-OS: Android, iOS
Web: Not tested

Additional context
The issue appears to stem from the library's internal validation rules for Belarusian phone numbers. Adjusting the validation logic to allow 9-digit numbers for country code BY would resolve this problem.