[FEATURE] Enable testing for python 3.13

[figueroa1395]

As found in 0310c66, even though power-grid-model-io supports Python 3.13, one of its dependencies, namely pandapower, does not. However, since this is a [dev] dependency and it's only used for testing purposes, we can solve it separately, i.e. with this issue. Furthermore, this issue is about enabling python 3.13 for testing in the CI.

Possible solutions

1. One possible way to go, and assuming pandapower doesn't support Python 3.13 soon, is to split the testing actions in two parts each: One for everything related with this dependency and the other for the rest. The first action, would be for Python 3.11 and 3.12 only, whereas the second would be tested in all supported Python versions available.
2. Another way, is to possibly wait until this is fixed on the dependency side, and only then upgrade the testing on the CI to Python 3.13.

My proposed solutions are not exhaustive, so feel free to add anything you might consider appropriate.

[mgovers]

What about using the version_info (https://docs.python.org/3/library/sys.html#sys.version_info) combined with pytest.mark.skip on the pandapower tests?