Add TEST_DATABASE_URL to configuration settings

- Introduced a new configuration variable, TEST_DATABASE_URL, to specify the test database connection string.
- This addition enhances the flexibility of database handling, particularly for testing scenarios, aligning with recent improvements in database URL management.

backend/core/config.py

@@ -27,6 +27,8 @@ class Settings(BaseSettings):
     CORE_DB_USER: str = "postgres"
     CORE_DB_PASSWORD: str = "postgres"
 
+    TEST_DATABASE_URL: str = "postgresql://postgres:postgres@localhost:5432/anexo76_core"
+
     # Keycloak
     KEYCLOAK_SERVER_URL: str = "http://localhost:8080/kcauth"
     KEYCLOAK_REALM: str = "master"