Skip sklearnex test when scikit-learn-intelex is unavailable

scikit-learn-intelex may not be installable with newer NumPy versions
(e.g. NumPy 2.4 from the updated Colab base image). Rather than fail
the entire test suite, skip the test gracefully when the module is
not present.

Author: stevemessick

tests/test_sklearnex.py

@@ -2,11 +2,18 @@
 
 import numpy as np
 
+try:
+    from sklearnex.cluster import DBSCAN
+    HAS_SKLEARNEX = True
+except ImportError:
+    HAS_SKLEARNEX = False
+
+@unittest.skipUnless(HAS_SKLEARNEX, 'scikit-learn-intelex is not installed')
 class TestSklearnex(unittest.TestCase):
     def test_dbscan(self):
         from sklearnex.cluster import DBSCAN
         X = np.array([[1., 2.], [2., 2.], [2., 3.],
             [8., 7.], [8., 8.], [25., 80.]], dtype=np.float32)
 
         clustering = DBSCAN(eps=3, min_samples=2).fit(X)
-        np.testing.assert_array_equal(np.array([0, 0, 0, 1, 1, -1]), clustering.labels_)
+        np.testing.assert_array_equal(np.array([0, 0, 0, 1, 1, -1]), clustering.labels_)