hypothesis-less environment test skip not working

Hi,

When hypothesis is not available, the @settings decorators throws an error in the test before the test gets to be skipped, e.g.:

======================================================================
ERROR: test_mccabe (unittest.loader._FailedTest)
----------------------------------------------------------------------
ImportError: Failed to import test module: test_mccabe
Traceback (most recent call last):
  File "/gnu/store/lp8ch4rn10whzyajnzv216d2a2v163c7-python-3.10.7/lib/python3.10/unittest/loader.py", line 436, in _find_test_path
    module = self._get_module_from_name(name)
  File "/gnu/store/lp8ch4rn10whzyajnzv216d2a2v163c7-python-3.10.7/lib/python3.10/unittest/loader.py", line 377, in _get_module_from_name
    __import__(name)
  File "/tmp/guix-build-python-mccabe-0.7.0.drv-0/mccabe-0.7.0/test_mccabe.py", line 244, in <module>
    @settings(
NameError: name 'settings' is not defined

Start with test_mccabe.py around line 244, where the @settings decorator is used, and reproduce the test collection failure in an environment without hypothesis. Trace how the hypothesis-dependent names are imported and how the test is intended to be skipped. Done means the suite collects successfully and skips the relevant test when hypothesis is unavailable.