feature(#13): update pytest.

tests/conftest.py

@@ -1,13 +1,14 @@
 import pytest
-from app import create_app
+from fastapi import FastAPI
+from fastapi.testclient import TestClient
 
 
 @pytest.fixture(scope="module")
 def test_client():
-    flask_app = create_app()
-
+    app = FastAPI()
+    client = TestClient(app)
     # Create a test client using the Flask application configured for testing
-    with flask_app.test_client() as testing_client:
+    with client as testing_client:
         # Establish an application context
-        with flask_app.app_context():
+        with client.app:
             yield testing_client  # this is where the testing happens!