add back pd.StringDtype check (#67)

Author: rjzamora

merlin/schema/schema.py

@@ -17,6 +17,7 @@
 from typing import Dict, List, Optional, Text, Union
 
 import numpy as np
+import pandas as pd
 
 from .tags import Tags, TagSet
 
@@ -53,6 +54,8 @@ def __post_init__(self):
                 dtype = np.dtype(self.dtype.numpy_dtype)
             elif hasattr(self.dtype, "_categories"):
                 dtype = self.dtype._categories.dtype
+            elif isinstance(self.dtype, pd.StringDtype):
+                dtype = np.dtype("O")
             else:
                 dtype = np.dtype(self.dtype)
         except TypeError as err: