cmake doesn't fail because of missing Python modules for testing (-DXEUS_ZMQ_BUILD_TESTS=ON)

[yurivict]

Tests just fail like this:

==================================== ERRORS ====================================
___________________ ERROR collecting test_kernel_control.py ____________________
ImportError while importing test module '/usr/ports/devel/xeus-zmq/work/.build/test/test_kernel_control.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
/usr/local/lib/python3.9/importlib/__init__.py:127: in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
test_kernel_control.py:2: in <module>
    import jupyter_kernel_test
E   ModuleNotFoundError: No module named 'jupyter_kernel_test'

cmake should look up Python and all required modules, and should print what modules were found.