Fix code scanning alert - Jinja2 templating with autoescape=False

[DavidPCoster]

This has medium priority but I'm not sure it is a real issue. This relates to how the templates are used.

Tracking issue for:

• https://github.com/UCL-CCS/EasyVVUQ/security/code-scanning/158

[djgroen]

I've just added the field to the Template function and at least locally it does not result in any testing failures...

[djgroen]

Okay, I forgot to tag the issue in the commit, but I just set autoescape to True instead of False. That should work properly, as I did check the jinja2 source code as well now :).