Fix the dpi related cron job failures (#875)

* add an int() call to fix test suite failures

* use round not int

kiva/tests/drawing_tester.py

@@ -186,7 +186,7 @@ def save_and_return_dpi(self):
         self.gc.save(filename)
         with Image.open(filename) as image:
             dpi = image.info['dpi']
-        return dpi[0]
+        return round(dpi[0])
 
     @contextlib.contextmanager
     def draw_and_check(self):