add pre-commit with checks (#142)

* add pre-commit

* fix isort and black repos

* add hooks,mypy and fix flake8

* add pre-commit installation and running ar CONTRIBUTING.MD

* edit Contributing

---------

Co-authored-by: Adrien Barbaresi <barbaresi@bbaw.de>

.pre-commit-config.yaml

@@ -0,0 +1,27 @@
+repos:
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v4.5.0
+    hooks:
+      - id: check-yaml
+      - id: end-of-file-fixer
+      - id: trailing-whitespace
+
+  - repo: https://github.com/psf/black
+    rev: 24.3.0
+    hooks:
+      - id: black
+
+  - repo: https://github.com/PyCQA/flake8
+    rev: 7.0.0
+    hooks:
+      - id: flake8
+
+  - repo: https://github.com/pycqa/isort
+    rev: 5.13.2
+    hooks:
+      - id: isort
+
+  - repo: https://github.com/pre-commit/mirrors-mypy
+    rev: v1.9.0
+    hooks:
+      - id: mypy

CONTRIBUTING.md

@@ -4,26 +4,39 @@ Thank you for considering contributing to htmldate!
 
 Here are some important resources:
 
-  * [List of currently open issues](https://github.com/adbar/htmldate/issues) (no pretention to exhaustivity!)
-  * [How to Contribute to Open Source](https://opensource.guide/how-to-contribute/)
+- [List of currently open issues](https://github.com/adbar/htmldate/issues) (no pretention to exhaustivity!)
+- [How to Contribute to Open Source](https://opensource.guide/how-to-contribute/)
 
 There are many ways to contribute, you could:
 
-  * Improve the documentation
-  * Find bugs and submit bug reports
-  * Submit feature requests
-  * Write tutorials or blog posts
-  * Write code
+- Improve the documentation
+- Find bugs and submit bug reports
+- Submit feature requests
+- Write tutorials or blog posts
+- Write code
+
+## Installing and Running Pre-commit
+
+### Introduction
+
+Pre-commit is a tool that helps maintain a consistent code style and quality in our project by running a set of hooks before each commit. These hooks perform checks such as code formatting, linting, and ensuring compliance with project-specific guidelines.
+
+### Installation and Running
+
+To install and set up pre-commit in your development environment, follow these steps:
+
+1. Run `pip install pre-commit` to your terminal to install pre-commit using pip.
+2. Navigate to your project directory and run `pre-commit install` to initialize pre-commit hooks.
+3. Run it manually on your changes using `git ls-files -- 'htmldate/*.py' | xargs pre-commit run --files`
 
 ## Submitting changes
 
 Please send a [GitHub Pull Request to htmldate](https://github.com/adbar/htmldate/pull/new/master) with a clear list of what you've done (read more about [pull requests](http://help.github.com/pull-requests/)).
 
 **Working on your first Pull Request?** You can learn how from this series: [How to Contribute to an Open Source Project on GitHub](https://egghead.io/series/how-to-contribute-to-an-open-source-project-on-github)
 
-For further questions you can contact me on [GitHub issues](), [Twitter](https://twitter.com/adbarbaresi) or by [E-Mail](http://adrien.barbaresi.eu/contact.html)
-
+For further questions you can contact me on [GitHub issues](https://github.com/adbar/htmldate/issues), [Twitter](https://twitter.com/adbarbaresi) or by [E-Mail](http://adrien.barbaresi.eu/contact.html)
 
 Thanks,
 
-Adrien
+Adrien