Added Docker support for building images and running tests with pytest

[gwpl]

This commit introduces a new commands in setup.py that allows users to build the Docker image and run pytest tests inside it.

The README.md file has been updated to document this new feature, providing clear instructions for users to take advantage of reproducible testing environments.

• python setup.py build_docker to facilitate Docker image building.
• python setup.py docker_test for running pytest tests within the Docker container.
• Enhanced README.md with instructions on how to use the new python setup.py build_docker and python setup.py docker_test commands.
• The new Docker-related setup commands ensure consistent testing environments across different systems.
• These additions help maintain uniformity in test execution and assist in the debugging process for developers and contributors.

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