Start moving build system to poetry

[yuriishizawa]

This PR include to repository the main files to start using Poetry as dependency manager, builder and publisher.

I've also modified some CI of test to use poetry instead of pip.
#278

Summary

This pull request includes changes that transition the project from using pip as a package manager to using Poetry. The changes affect multiple files in the project, including the build and testing workflows, the installation instructions, and the project metadata. The most significant changes are:

Transition to Poetry:

• .github/workflows/build.yml: The build workflow has been updated to use Poetry for dependency management and publishing the package to PyPI. The job name has been changed from build-n-publish to build-and-publish, and the build strategy now includes a matrix of Python and Poetry versions. The steps for building and publishing the package have also been updated to use Poetry.
• .github/workflows/testing.yml: The testing workflow has been updated to use Poetry for dependency management and running tests. The strategy matrix now includes a Poetry version, and the steps for installing dependencies and running tests have been updated to use Poetry.
• .travis.yml: The Travis CI configuration has been updated to use Poetry for installing dependencies and running tests.
• INSTALL: The installation instructions have been updated to include instructions for using Poetry to install the package.
• README.md: The README has been updated to include instructions for using Poetry to install the package. A new contributor has also been added to the list. [1] [2]
• poetry.toml: A new virtualenvs section has been added to the Poetry configuration, indicating that virtual environments should be created in the project directory.
• pyproject.toml: The project metadata has been updated to use Poetry, including the build system, package dependencies, and development dependencies. The package name, version, description, authors, license, and classifiers have also been updated.