Minimal change to avoid a numpy deprecation failure. Without this

all tests fail at python 3.10 and numpy 1.24.4. With it, they all pass.

pyfive/dataobjects.py

@@ -197,7 +197,7 @@ def _attr_value(self, dtype, buf, count, offset):
         """ Retrieve an HDF5 attribute value from a buffer. """
         if isinstance(dtype, tuple):
             dtype_class = dtype[0]
-            value = np.empty(count, dtype=np.object)
+            value = np.empty(count, dtype=object)
             for i in range(count):
                 if dtype_class == 'VLEN_STRING':
                     _, _, character_set = dtype