fix: requirements-dev.txt to reduce vulnerabilities

The following vulnerabilities are fixed by pinning transitive dependencies:
- https://snyk.io/vuln/SNYK-PYTHON-JINJA2-9292516

Author: snyk-bot

requirements-dev.txt

@@ -71,7 +71,7 @@ isoduration==20.11.0
     # via
     #   -r requirements.txt
     #   jsonschema
-jinja2==3.0.3
+jinja2==3.1.6
     # via
     #   -r requirements.txt
     #   mkdocs