IBMQ Backend: QasmSimulator will be deprecated

```
tests/test_ibmq_backend.py::test_ibmq_backend
  /..../lib/python3.9/site-packages/qiskit/providers/aer/backends/qasm_simulator.py:329: PendingDeprecationWarning: The `QasmSimulator` backend will be deprecated in the future. It has been superseded by the `AerSimulator` backend.
```