fix: use TestClient as context manager to trigger lifespan

tests/test_api.py

@@ -5,9 +5,8 @@ from src.naliiabotapi.main import app
 
 @pytest.fixture
 def client():
-    client = TestClient(app)
-
-    return client
+    with TestClient(app) as client:
+        yield client
 
 
 def test_root(client):