Fix: Adaptations for Pydantic v2 migration and stricter validation

- Improved error handling in `get_signed_pubkey` to align with stricter
JSON validation and date format requirements in Pydantic v2.
- Addressed warnings and deprecated functions raised during the migration to Pydantic v2.
- Updated type annotations to comply with Pydantic's stricter type checks
(`url` now requires proper type validation).
- Refactored test mocks to use `.model_dump_json()` instead of `.json()` for serialization
- Adjusted test cases to account for new fields in validation errors (`url`, `ctx`, and `input`)
introduced in Pydantic v2.
- Applied linting for style consistency across tests and codebase.

fix: yamlfix and pydantic are incompatible

Fix: HttpUrl no longer need scheme value

Author: Antonyjin