scripts: sphinx-pre-install: run on a supported version

scripts: sphinx-pre-install: run on a supported version

The scripts/sphinx-pre-install is used to detect problems at
the system environment and adjust it to build the Kernel
documentation. If the version is too old, it won't run, though.

Check if the version which started the script is valid. If not,
seek for a new one that is compatible with documentation
build.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/76627055a7f82f6a79296ddbd873fa5ac8f82a1d.1754992972.git.mchehab+huawei@kernel.org