Bump minimal versions of refman dependencies.

Fixes #11936.

Co-authored-by: Jim Fehrle <jfehrle@sbcglobal.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/doc/sphinx/conf.py b/doc/sphinx/conf.py
index 4136b406de..fabf7a519f 100755
--- a/doc/sphinx/conf.py
+++ b/doc/sphinx/conf.py
@@ -46,7 +46,7 @@ with open("refman-preamble.rst") as s:
 # -- General configuration ------------------------------------------------
 
 # If your documentation needs a minimal Sphinx version, state it here.
-needs_sphinx = '1.8.0'
+needs_sphinx = '2.3.1'
 
 # Add any Sphinx extension module names here, as strings. They can be
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom