updates to requirements.txt

The `requirements.txt` file should be updated to reflect the two different ways of generating certificates (jinja or cairo).

Should we have two different requirements files?

Start with requirements.txt and inspect how the project supports the Jinja and Cairo certificate-generation paths. Determine which dependencies each path requires and whether separate requirement files are needed; done means both documented approaches have reproducible dependency setup without unnecessary overlap.

Written by the indexing model from the issue text.