textproc/py-readthedocs-sphinx-ext: New Port

[agh_riseup.net]

Summary

Read the Docs Sphinx Extensions

The Sphinx extension that make Sphinx easier to use. Some extensions
require Read the Docs features, others are just extensions that and
enabled during builds of Read the Docs.

Currently packaged extensions include:

• An extension for building documentation like readthedocs.io. fame
• template-meta, allows users to specify template overrides in per-page context.

https://pypi.org/project/readthedocs-sphinx-ext/

This new Port is required for the tests framework for an update to textproc/py-sphinx_rtd_theme

[agh_riseup.net]

Move pytest from ${USES} to ${USE_PYTHON}

[agh_riseup.net]

Move pytest from ${USES} to ${USE_PYTHON} for real this time.

[arrowd]

Pushed in, thank you for your contribution.