Update developer toolset instructions in CONTRIBUTING.md

Author: Cjkjvfnby

CONTRIBUTING.md

@@ -74,19 +74,12 @@ We want your work to be readable by others; therefore, we encourage you to note
 
 - We encourage the use of Python [f-strings](https://realpython.com/python-f-strings/#f-strings-a-new-and-improved-way-to-format-strings-in-python) where they make the code easier to read.
 
-- Please consider running [__psf/black__](https://github.com/python/black) on your Python file(s) before submitting your pull request.  This is not yet a requirement but it does make your code more readable and automatically aligns it with much of [PEP 8](https://www.python.org/dev/peps/pep-0008/). There are other code formatters (autopep8, yapf) but the __black__ formatter is now hosted by the Python Software Foundation. To use it,
-
-  ```bash
-  python3 -m pip install black  # only required the first time
-  black .
-  ```
-
-- All submissions will need to pass the test `flake8 . --ignore=E203,W503 --max-line-length=88` before they will be accepted so if possible, try this test locally on your Python file(s) before submitting your pull request.
-
-  ```bash
-  python3 -m pip install flake8  # only required the first time
-  flake8 . --ignore=E203,W503  --max-line-length=88 --show-source
-  ```
+- Do not forget that running `pre-commit` checks locally will help you to follow code quality standards.
+  It will run a set of tools including
+  [black](https://github.com/psf/black),
+  [isort](https://github.com/PyCQA/isort),
+  [mypy](http://mypy-lang.org) and
+  [flake8](https://flake8.pycqa.org/en/latest/). 
 
 - Original code submission require docstrings or comments to describe your work.
 
@@ -148,15 +141,14 @@ We want your work to be readable by others; therefore, we encourage you to note
   starting_value = int(input("Please enter a starting value: ").strip())
   ```
 
-  The use of [Python type hints](https://docs.python.org/3/library/typing.html) is encouraged for function parameters and return values.  Our automated testing will run [mypy](http://mypy-lang.org) so run that locally before making your submission.
+  The use of [Python type hints](https://docs.python.org/3/library/typing.html) is encouraged for function parameters and return values. 
+  Our automated testing will run [mypy](http://mypy-lang.org) so run that locally with pre-commit before making your submission.
 
   ```python
   def sum_ab(a: int, b: int) -> int:
       return a + b
   ```
 
-  Instructions on how to install mypy can be found [here](https://github.com/python/mypy). Please use the command `mypy --ignore-missing-imports .` to test all files or `mypy --ignore-missing-imports path/to/file.py` to test a specific file.
-
 - [__List comprehensions and generators__](https://docs.python.org/3/tutorial/datastructures.html#list-comprehensions) are preferred over the use of `lambda`, `map`, `filter`, `reduce` but the important thing is to demonstrate the power of Python in code that is easy to read and maintain.
 
 - Avoid importing external libraries for basic algorithms. Only use those libraries for complicated algorithms.
@@ -172,7 +164,6 @@ We want your work to be readable by others; therefore, we encourage you to note
 - If you have modified/added documentation work, ensure your language is concise and contains no grammar errors.
 - Do not update the README.md or DIRECTORY.md file which will be periodically autogenerated by our GitHub Actions processes.
 - Add a corresponding explanation to [Algorithms-Explanation](https://github.com/TheAlgorithms/Algorithms-Explanation) (Optional but recommended).
-- All submissions will be tested with [__mypy__](http://www.mypy-lang.org) so we encourage you to add [__Python type hints__](https://docs.python.org/3/library/typing.html) where it makes sense to do so.
 
 - Most importantly,
   - __Be consistent in the use of these guidelines when submitting.__