[IMP] Upgrade Pydantic from V1 to V2

[orgis]

Upgrade Pydantic from v1 to v2

Description

This pull request upgrades the Pydantic dependency from version ^1.10.8 to ^2.8.2 and refactors the codebase to replace deprecated features with the new style introduced in Pydantic v2.

Changes

Dependencies

• Updated pydantic from ^1.10.8 to ^2.8.2 in pyproject.toml.

Code Refactoring

• Refactored GopayModel class to use Pydantic v2 model_config attribute instead of Config class.
• Ensured all (pydantic) model usages are up-to-date with Pydantic v2.

Testing

• Ran the full test suite to ensure all tests pass with the updated dependency.
• Three tests are failing (were failing before this change as well)
  • tests/test_api_payment.py::TestPayments::test_refund_payment
  • tests/test_api_recurrence.py::TestRecurrence::test_void_recurrence
  • tests/test_api_recurrence.py::TestRecurrence::test_create_next_ondemand_payment

Version

Changed package version from 2.0.2 to 3.0.0 as this can introduce breaking changes in codebases.

[geeshta]

I don't think this should be a major version bump as it doesn't affect the public API in any way.
Keep the version as is and we will include the rest of the PR in the next minor version release along with other stuff