CI: Add test job for Python 3.13

[EwoutH]

Python 3.13 is now in beta, thus is might be useful to start testing what works and what doesn't.

This PR adds a Python 3.13 job on Ubuntu.

[EwoutH]

Stuck on SciPy: scipy/scipy#16308 (comment)

[EwoutH]

Looks like SciPy 1.14.1 is incoming: scipy/scipy#21362

[EwoutH]

There's one single additional warning on Python 3.13:

ema_workbench/em_framework/futures_ipyparallel.py:15: DeprecationWarning: Parsing dates involving a day of month without a year specified is ambiguious
and fails to parse leap day. The default behavior will change in Python 3.15
to either always raise an exception or to use a different default year (TBD).
To avoid trouble, add a specific year to the input & format.
See python/cpython#70647.
from ipyparallel.engine.log import EnginePUBHandler