Fix deprecation warning by changing on_event to asynccontesxtmanager

app/main.py

@@ -1,17 +1,21 @@
 from fastapi import FastAPI
 from fastapi.security import OAuth2PasswordBearer
+from contextlib import asynccontextmanager
 from .controllers import userManager, cardManager, groupManager, aaManager
 from .services.database import create_db_and_tables
 from .services.auth import token_router, create_first_user
 
 oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")
 
-app = FastAPI()
-@app.on_event("startup")
-def on_startup():
+@asynccontextmanager
+async def lifespan(app: FastAPI):
     create_db_and_tables()
     create_first_user()
     print("Database created and tables initialized.")
+    yield
+
+app = FastAPI(lifespan=lifespan)
+
 
 
 app.include_router(token_router)