In Python 3.12, has_calls is not a valid assertion.
Closes: #1058421
Tests:
- Run "python3.12 -m pytest plinth/tests/test_operation.py" in unstable
container. All tests are passed.
Signed-off-by: James Valleroy <jvalleroy@mailbox.org>
Reviewed-by: Sunil Mohan Adapa <sunil@medhas.org>