doc: update sphinx to 3.2.1 in the hope that it fixes the current errors

diff --git a/docs/requirements.txt b/docs/requirements.txt
index 0f9b45d..a3e1aa5 100644 (file)
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -1,4 +1,4 @@
 breathe
-sphinx>=1.8.0
+sphinx>=3.2.1
 sphinx_rtd_theme
 sphinx_tabs