Fix random.sample() usage with set for Python 3.11 compatibility (GH#887)

[Aniketsy]

This PR resolves a compatibility issue with Python 3.11 and above, where passing a set directly to random.sample() raises a TypeError.

In util.py, the open_qubits set is now explicitly converted to a list before being passed to random.sample() in the _apply_random_control function.

Audit of other random.sample() calls in util.py: No changes needed

Line 150: qubits is expected to be a list or tuple .
locs = tuple(random.sample(qubits, n_qubits))

Line 199: Same as above, qubits is a tuple.
locs = tuple(random.sample(qubits, n_qubits))

Line 253: qubits is a list.
this_term_qubits = random.sample(qubits, term_length)

Line 255: paulis is a list.
[random.sample(paulis,1)[0] for _ in range(term_length)]

Please let me know if this fix needs any improvements . I’m open to feedback and happy to make changes based on suggestions.
Thankyou!