chore: update Sphinx version

[kenjis]

Description

• update sphinx, sphinxcontrib-phpdomain

Checklist:

• Securely signed commits
• [] Component(s) with PHPDoc blocks, only if necessary or adds value
• [] Unit testing, with >80% coverage
• [] User guide updated
• [] Conforms to style guide

[kenjis]

I've update Sphinx version on my local, but still :php:meth does not work.

:php:meth:`Response::setCookie() <CodeIgniter\\HTTP\\Response::setCookie>`

See https://github.com/markstory/sphinxcontrib-phpdomain#quick-sample

[MGatner]

I don't know about the class issue but the version bump seems good.