Adding tests to the climate, reports, and taxonomy apps

[clorenquecan]

This pull request introduces model test coverage for various apps.

Model Test Coverage

• Organized tests within dedicated tests directories inside each app in files test_model.py.
• Included tests for __str__ methods to ensure expected behavior.

Fixtures & Data Setup

• I used the existing factories and fixtures, and defined the missing trait fixture in the conftest.py

Note: The test cases for the places, and biodiversity apps were already merged in a previous PRs.
I also install and run pre-commit locally as per @dr-rompecabezas suggestion (Thanks very useful!)

Closes #22

[clorenquecan]

Adding back TrailFactory

[dr-rompecabezas]

Thanks, @clorenquecan!