From 5b0c2d88b4bf1c1b31f568d7c464d3db9dec367c Mon Sep 17 00:00:00 2001
From: Eric Prestat <eric.prestat@gmail.com>
Date: Wed, 10 Jan 2024 20:10:42 +0000
Subject: [PATCH] Install optipng to avoid warning when building doc and
 workflow failure

---
 .github/workflows/doc.yml | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/doc.yml b/.github/workflows/doc.yml
index e9af4c8bc1..490185fc59 100644
--- a/.github/workflows/doc.yml
+++ b/.github/workflows/doc.yml
@@ -10,4 +10,5 @@ jobs:
       # install with speed extra to avoid warnings
       pip_extra_doc: 'doc,speed'
       # graphviz is required to build mermaid graph
-      install_package_ubuntu: graphviz
+      # optipng is required to optimize thumbnail
+      install_package_ubuntu: graphviz, optipng