Fix IndexSeries/data warning

Author: rly

tests/integration/hdf5/test_image.py

@@ -39,7 +39,7 @@ def setUpContainer(self):
 
         iS = IndexSeries(
             name='test_iS',
-            data=[1, 2, 3],
+            data=np.uint([1, 2, 3]),
             unit='N/A',
             indexed_images=self.images,
             timestamps=[0.1, 0.2, 0.3]