Fix documentation build

extras/docs.txt

@@ -4,7 +4,7 @@ pdf2image>=1.16,<1.17
 pytest
 Sphinx>=5.1,<5.2
 nbsphinx>=0.8,<0.9
-sphinx-rtd-theme>=1.0,<1.1
+sphinx-rtd-theme>=2.0,<3.0
 sphinx-argparse>=0.5.1
 sphinxcontrib-applehelp>=1.0,<1.1
 sphinxcontrib-devhelp>=1.0,<1.1