Defer numpy import on first pass of setup.py

setup.py

@@ -4,7 +4,13 @@
 import platform
 import sys
 
-import numpy
+try:
+ import numpy
+except:
+ from unittest.mock import MagicMock
+ sys.modules["numpy"] = MagicMock()
+ import numpy
+
 from setuptools import Extension, setup
 from setuptools.command.test import test as TestCommand
 import versioneer