Feat(API): PostgreSQL database setup

- Fix enviroment variables
- Fix the ping route for API
- Added database connection for future testing

backend/tests/blueprints/test_control.py

@@ -1,8 +1,7 @@
-from quart import Response
-from backend.run import app
+from quart import Quart
 
 
-async def test_control() -> None:
+async def test_control(app: Quart) -> None:
     test_client = app.test_client()
-    response: Response = await test_client.get("/control/ping")
+    response = await test_client.get("/control/ping/")
     assert (await response.get_json())["ping"] == "pong"