refactor: make settings a fixture

tests/api/test_api.py

@@ -18,7 +18,10 @@ from ..helpers import (
 async def test_create_account(client, settings: Settings):
     settings.lnbits_allow_new_accounts = False
     response = await client.post("/api/v1/account", json={"name": "test"})
-    assert response.status_code == 403
+
+    assert response.status_code == 400
+    assert response.json().get("detail") == "Account creation is disabled."
+
     settings.lnbits_allow_new_accounts = True
     response = await client.post("/api/v1/account", json={"name": "test"})
     assert response.status_code == 200