Also check for DJango in pyproject.toml

[afiestas]

Poetry, supported by Oryx, declares its dependencies in the standard pyproject.toml file. Some other tools also use this file for dependency declaration.

This change enables the detection of Django when dependencies are installed via Poetry (and other tools) by also checking for Django in the pyproject.toml file.

I haven't been able to locate any test that uses or checks for requirements.txt.