- new doc dependencies: `mkdocs`, `mkdocs-material` and `mkdocstrings`
- auto reference documentation using `mkdocstrings`
- moves `pytest` to "tests" dependency group
- install only pytest for testing in github-ci
- adds pre-commit-hooks

**Related Items**

*Issues*

- Closes python-validators#169

*PRs*

- Closes python-validators#173