Set up pre-commit hooks

- add pre-commit hooks:
  + run `nox -s lint` on staged *.py files
  + run common pre-commit hooks for validations that could not be
    achieved with tools in the develop environment so easily
- add pre-merge hook:
  + run `nox -s _pre-commit-test-hook` before merges
    * ignores the paths to staged files
      passed in by the pre-commit framework
    * runs all test cases instead

README.md

@@ -95,6 +95,13 @@ The second task lints all source code files with
     [ruff](https://pypi.org/project/ruff/).
 `flake8` is configured with a couple of plug-ins.
 
+You may want to install the [pre-commit](https://pre-commit.com/) hooks
+    that come with the project:
+
+`nox -s pre-commit-install`
+
+Then, the linting and testing occurs automatically before every commit.
+
 
 #### Test Suite