jinga error is appeared while buildig in readthedocs

error:  AttributeError: module 'jinja2' has no attribute 'contextfilter'
trial solution: readthedocs/readthedocs.org#9064 (comment)
made requirements.txt with: https://github.com/bndr/pipreqs

Author: atifkarim

.readthedocs.yaml

@@ -15,6 +15,6 @@ mkdocs:
   configuration: mkdocs.yml
 
 # Optionally declare the Python requirements required to build your docs
-# python:
-#    install:
-#    - requirements: docs/requirements.txt
+python:
+   install:
+   - requirements: docs/requirements.txt

docs/requirements.txt

@@ -0,0 +1,2 @@
+
+jinja2<3.1.0