[docs] [issue35605] backported patch requires new sphinx, minimum sphinx version was not bumped

[Karthikeyan Singaravelan]

Change by Karthikeyan Singaravelan <tir.karthi at gmail.com>:


----------
nosy: +mdk, steve.dower

_______________________________________
Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue35605>
_______________________________________