put tempfile import in separate try statement

because install shouldn't fail just because someone doesn't have
setuptools...

setup.py

@@ -7,8 +7,13 @@ from __future__ import print_function, unicode_literals
 import os
 import sys
 import json
+
 try:
     from tempfile import TemporaryDirectory
+except ImportError:
+    pass
+
+try:
     from setuptools import setup
     from setuptools.command.sdist import sdist
     from setuptools.command.install import install