add jinja to build

Author: tsolakoua

.github/workflows/build.yml

@@ -23,6 +23,7 @@ jobs:
           python -m pip install sphinx==3.4.1
           pip install tox==3.20.0
           python -m pip install sphinx_rtd_theme==0.5.2
+          pip install Jinja2<3.1
           pip install virtualenv
       - name: Test with tox
         run: |