Changing optimization solutions

[nwittler]

Describe the bug The optimization in examples/two_qubits.ipynb did not converge to high accuracy after 8e747d5fb23d7c78041ec3af8a6f5869df30efee

To Reproduce Rerun the notebook.

Workaround The issue is fixed by extending the search bounds of the optimization, as done in 71c4c093da391bc7fca6d4ffab37f358819c2269

Open questions

• What changed to cause a different solution?
• Why don't the existing tests catch this? We test propagation and signal generation. Maybe not careful enough?
• How do we test against this?

[GlaserN]

This might be related to why tests of https://github.com/q-optimize/c3/pull/89 fail. The test were actually running smoothely on a windows machine, but the signals generation is different on linux for an at the moment unknown reason.

[lazyoracle]

Related: #71 to introduce Property Based Tests