fix categorize warnings

Author: alimanfoo

zarr/tests/test_filters.py

@@ -169,8 +169,8 @@ def test_array_with_packbits_filter():
 def test_array_with_categorize_filter():
 
     # setup
-    data = np.random.choice([b'foo', b'bar', b'baz'], size=100)
-    flt = Categorize(dtype=data.dtype, labels=['foo', 'bar', 'baz'])
+    data = np.random.choice([u'foo', u'bar', u'baz'], size=100)
+    flt = Categorize(dtype=data.dtype, labels=[u'foo', u'bar', u'baz'])
     filters = [flt]
 
     for compressor in compressors: