[Python] Writing pandas.DataFrame containing a object dtype column with int values fails

### Describe the bug, including details regarding any error messages, version, and platform.

I have a pandas.DataFrame with column 电源状态 whose unique values are :

df['电源状态'].unique() -> array(['静置', 'CC充电', 'CC放电', 'CV', 46], dtype=object)
df['电源状态'].dtype -> dtype('O') (dtype auto generated during read)

Upon performing df.to_feather('test.feather'), the following error raises:

ArrowTypeError: ("Expected bytes, got a 'int' object", 'Conversion failed for column 电源状态 with type object')

### Component(s)

Python