fix: requirements.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.txt

@@ -24,7 +24,7 @@ greenlet==2.0.1
 gunicorn==20.1.0
 humanize==4.4.0
 idna==3.4
-Jinja2==3.1.2
+Jinja2==3.1.6
 kiwisolver==1.4.4
 MarkupSafe==2.1.1
 matplotlib==3.6.2