chore: fix ImportError

ImportError: cannot import name 'environmentfilter' from 'jinja2' (/usr/local/lib/python3.10/site-packages/jinja2/__init__.py)
See sphinx-doc/sphinx#10291

Author: kenjis

user_guide_src/requirements.txt

@@ -2,3 +2,4 @@ sphinx>=2.4.4,<3
 sphinxcontrib-phpdomain>=0.7.1
 docutils>=0.16
 sphinx-rtd-theme>=0.5.0
+jinja2<3.1