Hea init bug

[alexfleury-sb]

Init of the HEA raises an error if the the number of qubits and electrons are specified.

    if not (bool(molecule) ^ (bool(n_qubits) and (bool(n_electrons) | reference_state == "zero"))):
TypeError: unsupported operand type(s) for |: 'bool' and 'str'

It is especially annoying when working with a QubitOperator as an input.