Add CI tests for `py3.13` after final release

[edoaltamura]

What should we add?

Python 3.13 is scheduled to be released in its final version in October 2024, as outlined in PEP 719. This setup should be included in the CI test suite soon after the final release of Python 3.13.

[edoaltamura]

The final release of Python 3.13 is scheduled for next Monday, 7 October. So, we could start preparing the update to increase the maximum supported version.

[woodsp-ibm]

FYI: Qiskit has an open issue to support 3.13 Qiskit/qiskit#12903

[edoaltamura]

Removing the milestone pin because Qiskit 1.3 with Py3.13 support might not be released by the time our 0.8.0 is out. In this way, we can merge this update asynchronously to the release schedule.