Update dependency Jinja2 to v3

Author: renovate-bot

requirements.txt

@@ -8,7 +8,7 @@ Flask-Assets==2.0
 iniconfig==1.1.1
 isort==5.6.4
 itsdangerous==1.1.0
-Jinja2==2.11.2
+Jinja2==3.1.1
 jsmin==2.2.2
 lesscpy==0.14.0
 MarkupSafe==1.1.1