Update Jinja2
Update Jinja2

The previous version will soon receive a CVE which is not relevant for
us, but let's make tools that only look at the version (e.g. GitHub's
security notifications) happy.

DirkHoffmann/indico,indico/indico,pferreir/indico,pferreir/indico,ThiefMaster/indico,ThiefMaster/indico,ThiefMaster/indico,DirkHoffmann/indico,ThiefMaster/indico,indico/indico,indico/indico,DirkHoffmann/indico,indico/indico,DirkHoffmann/indico,pferreir/indico,pferreir/indico