Customizing the Jinja2 environment

The special template variable _jinja2_env_vars can be used to customize the [Jinja2 environment](https://jinja.palletsprojects.com/en/3.1.x/api/#jinja2.Environment).

This example shows how to control whitespace with lstrip_blocks and trim_blocks:

{
    "project_slug": "sample",
    "_jinja2_env_vars": {"lstrip_blocks": true, "trim_blocks": true}
}