Update requirements.txt

Author: svekars

.ci/docker/requirements.txt

@@ -6,7 +6,7 @@ sphinx==7.2.6
 sphinx-gallery==0.19.0
 sphinx_design==0.6.1
 sphinxext-opengraph==0.10.0
-docutils==0.21.2
+docutils>=0.18.1,<0.21
 sphinx-copybutton==0.5.2
 sphinx_sitemap==2.7.1
 sphinxcontrib-mermaid==1.0.0