TST: Skip Cython test for editable install

[skip circle]

Author: thalassemia

numpy/random/tests/test_extending.py

@@ -46,6 +46,10 @@
         cython = None
 
 
+@pytest.mark.skipif(
+    'editable' in np.__path__[0],
+    reason='Editable install cannot find .pxd headers'
+)
 @pytest.mark.skipif(
         sys.platform == "win32" and sys.maxsize < 2**32,
         reason="Failing in 32-bit Windows wheel build job, skip for now"