I have a normal pandas DataFrame which contains some string columns. I am converting the dtypes to string[pyarrow]

symbol_exch = pd.DataFrame(
    [
        {'exchange': s['exchange'], 'symbol': s['symbol']}
        for s in exchange.symbols
    ],
)
symbol_exch = symbol_exch.astype(
    dtype={'exchange': 'string[pyarrow]', 'symbol': 'string[pyarrow]'},
)

As can be seen, the dtypes are reported as string[pyarrow]:

>>> symbol_exch.dtypes
exchange    string[pyarrow]
symbol      string[pyarrow]
dtype: object

I now have a dask.dataframe which I am trying to merge with the above:

df = dask.dataframe.from_delayed(tasks, meta)
df = df.merge(symbol_exch, on='symbol', how='left')

Whilst the operation completes successfully, dask issues a warning:

/usr/local/lib/python3.10/site-packages/dask/dataframe/multi.py:520: UserWarning: Merging dataframes with merge column data type mismatches: 
+----------------------+-----------------+-------------+
| Merge columns        | left dtype      | right dtype |
+----------------------+-----------------+-------------+
| ('symbol', 'symbol') | string[pyarrow] | string      |
+----------------------+-----------------+-------------+
Cast dtypes explicitly to avoid unexpected results.
  warnings.warn(

Even though I explicitly set the dtypes in the right-hand dataframe, the warning is still issued.

What do I need to do to my symbol_exch dataframe in order to suppress this warning?