We publish the docs to readthedocs.io

We publish the test coverage reporting to codecov.io

The xdoctest integration in pytest (see tests/test_docstrings.py)
is prone to miss docstrings in new source files as they must be
included in the test case explicitly.

So, to play it safe, we run the nox session "test-docstrings" on CI.

- 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

- use sphinx to document the developed package
- create nox session "docs" to build the docs

- use pip-audit to check the project's dependencies for known
  security vulnerabilities and exploits
- add nox sessions "audit" and "audit-updates" to run
  the above checks against the pinned and unpinned dependencies

- the nox session "test-coverage" triggers further nox sessions
  that run the test suite for all supported Python versions
- the nox session "_test-coverage-run" runs the test suite for
  a particular Python version using the coverage tool
- the nox session "_test-coverage-report" combines the individual
  coverage reports

- use xdoctest to validate code snippets in docstrings
- make xdoctest part of the nox session "test" via
  the new `test_docstrings()` test case
- add nox session "test-docstrings" for convenience;
  also, `xdoctest.doctest_module()` does not discover
  docstrings that are imported at the root of the package
  => each new module with docstrings must be added to
     `test_docstrings()` by hand, which is likely forgotten
  => the nox session "test-docstrings" should run on CI

- `lalib.__version__` is dynamically assigned
- the format is "x.y.z[.dev0|aN|bN|rcN|.postM]"
  where x, y, z, M, and N are non-negative integers
  + x, y, and z model the "major", "minor", and "patch"
    parts of semantic versioning
    (See: https://semver.org/#semantic-versioning-200)
  + M is a single digit and N either 1 or 2
  => This complies with (a strict subset of) PEP440
- add unit tests for the `__version__` identifier

- use pytest as the test suite and
  measure test coverage with coverage.py
- add package for the test suite under tests/
- add nox session "test" to run the test suite
  for all supported Python versions
- use flake8 to lint pytest for consistent style

- use flake8 as the main linting tool with the following plug-ins:
  + flake8-annotations
  + flake8-bandit
  + flake8-black
  + flake8-broken-line
  + flake8-bugbear
  + flake8-commas
  + flake8-comprehensions
  + flake8-debugger
  + flake8-docstrings
  + flake8-eradicate
  + flake8-isort
  + flake8-quotes
  + flake8-string-format
  + flake8-pyproject
  + pep8-naming
  + pydoclint
- use mypy for static type checking
- use ruff for linting for future compatibility
- add nox session "lint" to run these tools
- add `ruff check --fix ...` in nox session "format"
- lint all source files => no errors found

- auto-format code with:
  + autoflake => * remove unused imports and variables
                 * remove duplicate dict keys
                 * expand star imports
  + black => enforce an uncompromising code style
  + isort => enforce a consistent import style
             compliant with Google's Python style guide
- add nox session "format" to run these tools

- base configuration for all nox sessions to come
- add infos about nox in the README file
- ignore [py]cache folders in git

- describe how a local develop environment can be set up
- we use poetry to manage the project
  => add pyproject.toml and poetry.lock files
- add a package for the source code
  => "src" layout structure to ensure that pytest runs the tests
     against a packaged version installed in a virtual environment
     and not the *.py files in the project directory
     (Source: https://hynek.me/articles/testing-packaging/)
- ignore poetry's artifacts in git

- describe the project's goals
- contributions are welcome
- mention the GitFlow branching model

MIT license because the project is for everybody