Add GitHub Action to automate publishing to PyPI

[jank324]

Description

Adds a GitHub Action pypi.yaml that automatically publishes to PyPI and creates a GitHub Release when a tag names t... is created.

Motivation and Context

• I have raised an issue to propose this change (required for new features and bug fixes)

So far, to create a release, I always have to go in and manually build and upload the package.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (update in the documentation)

Checklist

• I have updated the changelog accordingly (required).
• My change requires a change to the documentation.
• I have updated the tests accordingly (required for a bug fix or a new feature).
• I have updated the documentation accordingly.
• I have reformatted the code and checked that formatting passes (required).
• I have have fixed all issues found by flake8 (required).
• I have ensured that all pytest tests pass (required).
• I have run pytest on a machine with a CUDA GPU and made sure all tests pass (required).
• I have checked that the documentation builds (required).

Note: We are using a maximum length of 88 characters per line.

[Copilot]

Pull Request Overview

This PR introduces a new GitHub Action that automates the process of publishing the Python package to PyPI and creating a corresponding GitHub Release when a new tag is pushed. Key changes include:

• Updating the CHANGELOG to record the new automation feature.
• Adding a new GitHub Actions workflow file (.github/workflows/pypi.yaml) to build, publish, and sign the Python package.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
CHANGELOG.md	Updated to include an entry for the PyPI publishing feature.
.github/workflows/pypi.yaml	New workflow file that builds the package, publishes it to PyPI, signs the distributions, and creates a GitHub Release.

[jank324]

This is where I more or less got this from: https://packaging.python.org/en/latest/guides/publishing-package-distribution-releases-using-github-actions-ci-cd-workflows/