Verify all examples work with Python 3.11

[dpinte]

• verify all examples in https://github.com/enthought/enable/tree/main/enable/examples and https://github.com/enthought/enable/tree/main/kiva/examples run as expected
• verify the intergration with etsdemo (see traitsui)

[homosapien-lcy]

New tests are added and past (python 3.7-3.11) in PR #1017

[dpinte]

@homosapien-lcy Can you confirm the examples available here: https://github.com/enthought/enable/tree/main/enable/examples are covered by the tests? I suspect they are not. And because some of them have user interactions expected, the best should be to make a list, run them by hand and confirms they work as appropriate.