Pytest warning fix for contract test contract_update_without_create

[carpnick]

Issue #, if available:

Description of changes:

Fix warning below when running Contract tests

Pytest warning when running contract tests:

resource/handler_update_invalid.py::contract_update_without_create
  /opt/homebrew/lib/python3.10/site-packages/_pytest/python.py:199: PytestReturnNotNoneWarning: Expected None, but resource/handler_update_invalid.py::contract_update_without_create returned <HandlerErrorCode.NotFound: 'NotFound'>, which will be an error in a future version of pytest.  Did you mean to use `assert` instead of `return`?
    warnings.warn(

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[mmaeng]

Looks like there is a formatting/linting change that pre-commit wants to do. But LGTM with that update