[I] Saving/loading dictionary type using pyarrow is broken [arrow]

[via GitHub]

scravy opened a new issue, #44350:
URL: https://github.com/apache/arrow/issues/44350

   ### Describe the bug, including details regarding any error messages, 
version, and platform.
   
   When defining a column as dictionary from int32 → binary16, saving that as 
parquet, and reading it back – the schema is not the same as the one written, 
see example:
   
   ```
   from tempfile import NamedTemporaryFile
   
   import pyarrow as pa
   import pyarrow.parquet as pq
   
   if __name__ == "__main__":
       z = b"\0" * 16
       B16 = pa.binary(16)
       D32dict = pa.dictionary(pa.int32(), B16)
       tbl = pa.Table.from_arrays([[z, z, z, z]], names=["clmn"])
       tbl = tbl.set_column(0, "clmn", tbl["clmn"].cast(D32dict))
       assert (
           tbl.schema.field("clmn").type == D32dict
       ), f"{tbl.schema.field('clmn').type} ≠ {D32dict}"
       with NamedTemporaryFile() as fn:
           pq.write_table(tbl, fn)
           t = pq.read_table(fn)
           assert (
               t.schema.field("clmn").type == D32dict
           ), f"schema of table read is broken: {t.schema.field('clmn').type} ≠ 
{D32dict}"
   ```
   
   ### Component(s)
   
   Parquet


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