use the latest version of pyquery as python3 is now available by default

.github/workflows/build_doc.yml

@@ -56,7 +56,7 @@ jobs:
           set -x
           sudo apt-get update && sudo apt-get install -y graphviz ssh bibtex2html
           sudo pip install lxml
-          sudo pip install 'pyquery==1.4.1' # it seems to be the last py2 compatible version
+          sudo pip install pyquery
           wget --no-verbose -O doxygen_exe https://cgal.geometryfactory.com/~cgaltest/doxygen_1_8_13_patched/doxygen
           sudo mv doxygen_exe /usr/bin/doxygen
           sudo chmod +x /usr/bin/doxygen