Correcting typo

app/main.py

@@ -19,7 +19,7 @@ app = FastAPI()
 async def db_session_middleware(request: Request, call_next):
     response = Response("Internal server error", status_code=500)
     try:
-        request.state.db = SessionLocal
+        request.state.db = SessionLocal()
         response = await call_next(request)
     finally:
         request.state.db.close()