Clean up testfunctions.ipynb by removing redundant code

Removed outdated and unused code snippets from testfunctions.ipynb to streamline the notebook. This improves readability and reduces clutter, ensuring the file contains only relevant and functional code samples.

backend/tests/test_contact.py

@@ -7,7 +7,7 @@ client = TestClient(app)
 def authenticate():
     # Simulate login to obtain token
     response = client.post(
-        "/auth/token/login", json={"username": "testuser", "password": "testpass"}
+        "/auth/token/login", data={"username": "testuser", "password": "testpass"}
     )
     assert response.status_code == 200
     return response.json()["access_token"]