Incorrect README sphinx version

[t92549]

The README states the default sphinx version is 5.3:

pages/README.rst

Line 100 in e208343

``sphinx_version`` ``5.3`` false Version of Sphinx

However, there is no default version, so latest is used:

pages/action.yml

Lines 25 to 28 in e208343

	sphinx_version:
	description: 'Version of Sphinx'
	required: false
	default: ''

[SilverRainZ]

Thanks for your report!