feat: add PyPI trusted publishing

[adarshdigievo]

This PR modernizes the release process by replacing long-lived PyPI API tokens with PyPI Trusted Publishing.

• This is now the recommended way to publish Python packages and prevents the risks of long-lived PyPI API tokens.
• Trusted publishing uses GitHub Actions OIDC for secure authentication.

Changes made:

• Replaced token-based PyPI publishing with OIDC Trusted Publishing using the protected pypi GitHub environment.
• Removed the PYPI_API_TOKEN requirement
• Added Python 3.14 to the CI and release test matrices and moved example tests to Python 3.14.
• PyPI account setup for trusted publishing is already completed. The workflow will run starting with the next release, with no further configuration needed on the GitHub repo or PyPI.

[Copilot]

Pull request overview

This PR updates the project’s GitHub Actions workflows to publish releases to PyPI via Trusted Publishing (OIDC) instead of a long-lived PyPI API token, and expands CI/release testing to include Python 3.14.

Changes:

• Switch PyPI publishing in the release workflow from twine + PYPI_API_TOKEN to pypa/gh-action-pypi-publish with OIDC and a protected pypi environment.
• Add Python 3.14 to CI and release matrices, and run example tests on 3.14.
• Update README publishing docs to remove the PYPI_API_TOKEN secret requirement.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
README.md	Removes PYPI_API_TOKEN from documented required secrets, aligning docs with OIDC trusted publishing.
.github/workflows/release.yml	Adds Python 3.14 to the release test matrix and switches publishing to OIDC trusted publishing (with pypi environment + id-token).
.github/workflows/ci.yml	Adds Python 3.14 to CI matrix and moves example tests to run on 3.14.

Comments suppressed due to low confidence (1)

.github/workflows/release.yml:23

• actions/checkout@v6 and actions/setup-python@v6 are not valid major versions. Use the current supported major versions so the workflow doesn’t fail at runtime (checkout v7, setup-python v5).

      - uses: actions/checkout@v6

      - uses: actions/setup-python@v6
        with:
          python-version: ${{ matrix.python-version }}

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