Semversioner

- minor: Expose models to use semversioner as a library.
- minor: Use models for better encapsulation and code refactoring.

- major: Drop support for Python 3.6.
- minor: Add type hinting.
- minor: Bump click dependency to 8.0.3.
- minor: Bump jinja2 dependency to 3.0.3.
- patch: Add Python 3.10 testing in the CI/CD process.
- patch: Bump importlib_resources dependency to 5.4.0.
- patch: Bump pytest dependency to 6.2.5.
- patch: Bump twine dependency to 3.7.1.
- patch: Bump wheel dependency to 0.37.0.
- patch: Remove unnecessary dependency: colorama.
- patch: Rename semversioner directory to .semversioner.

- minor: Add support for custom changelog template
- patch: Fix security vulnerability with jinja2 CVE-2020-28493

- minor: Improved performance by supporting multiple changeset files per second
- minor: Status command now sorts unreleased changes by type and description in order to display consistent results
- patch: Internal code refactor to improve code readability and maintanability

- minor: Add '--version' filter to the 'changelog' command to display the changelog only for a specific version

- minor: Add new 'status' command to display the state of the working directory and unreleased changes
- patch: Fix build and deployment configuration
- patch: Refactor method names and code for better code readability and testability