chore(docs): upgrade sphinx

[Rotzbua]

Changes

• upgrade sphinx
• use numpy doc style

[mwtoews]

Do you have any idea why this code block changes the rendered output to this?

Maybe it needs .. code-block:: none?

[Rotzbua]

@mwtoews good catch. changed.

[Copilot]

Pull request overview

This PR updates the project’s documentation toolchain/configuration to support a Sphinx upgrade and to render docs using NumPy-style docstrings/directives.

Changes:

• Upgrades the docs dependency to a newer Sphinx version.
• Updates docstring/README reST markup to use explicit .. code-block:: directives.
• Adjusts Sphinx/Read the Docs configuration (extensions, exclusions, build image, install method).

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/affine/__init__.py	Tweaks the Affine class docstring to be more NumPy-style and uses code-block for the matrix example.
docs/src/conf.py	Updates Sphinx config: extensions, exclude patterns, and copyright metadata.
docs/requirements.txt	Pins docs build Sphinx version to the upgraded release.
README.rst	Replaces a literal block (::) with an explicit code-block directive for the matrix example.
.readthedocs.yaml	Updates RTD build OS/Python version and installs the package via pip during doc builds.

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[sgillies]

Re-ran the failed docs build and it passed. Merging.