Python-amazon-paapi

**Updates:**
- Added Belgium region.

**Fixes:**
- Fixed lint and tests execution on PR creation.

**Breaking changes:**
- Exceptions have been renamed, check [documentation](https://python-amazon-paapi.readthedocs.io/en/latest/pages/migration-guide-5.html#what-should-i-change-in-my-current-code) for more info.
- Removed the old `amazon` module.

**Code quality:**
- Code formatted using black and isort.
- Solved errors found by flake8 and pylint.
- Increased tests coverage to 100%.
- Added scripts for linting and testing code.
- Added pre-push githook.
- Added new GitHub Action to run linting and tests.
- Added SonarCloud integration to check for issues and test coverage.

**Documentation:**
- Added `Contribution` section to `README`.
- Added new migration section to [documentation](https://python-amazon-paapi.readthedocs.io/en/latest/pages/migration-guide-5.html).

**Improvements:**
- Improved type hints.

**Improvements:**
- Improved type hints.
- Added new parameter to product information.

**Changes:**
- Added new `price_type` and `price_type_label` parameters.

**Fixes:**
- Fixed typo in `ItemsNotFoudException` and changed to `ItemsNotFoundException`.

**Fixes:**
- Added search_index to search mandatory args check.