Add comprehensive tests for Parks API and models

- Implemented extensive test cases for the Parks API, covering endpoints for listing, retrieving, creating, updating, and deleting parks.
- Added tests for filtering, searching, and ordering parks in the API.
- Created tests for error handling in the API, including malformed JSON and unsupported methods.
- Developed model tests for Park, ParkArea, Company, and ParkReview models, ensuring validation and constraints are enforced.
- Introduced utility mixins for API and model testing to streamline assertions and enhance test readability.
- Included integration tests to validate complete workflows involving park creation, retrieval, updating, and deletion.

parks/models/areas.py

@@ -9,6 +9,11 @@ from .parks import Park
 
 @pghistory.track()
 class ParkArea(TrackedModel):
+    
+    # Import managers
+    from ..managers import ParkAreaManager
+    
+    objects = ParkAreaManager()
     id: int  # Type hint for Django's automatic id field
     park = models.ForeignKey(Park, on_delete=models.CASCADE, related_name="areas")
     name = models.CharField(max_length=255)