BUG: string[pyarrow] dtype not loaded from feather
### 

- [X] I have checked that this issue has not already been reported.

- [x] I have confirmed this bug exists on the [latest version](https://pandas.pydata.org/docs/whatsnew/index.html) of pandas.

- [x] I have confirmed this bug exists on the master branch of pandas.


### Reproducible Example

```python
s = pd.DataFrame({'s':['aaa', 'bbb', 'ccc']})
print(f'Initial df bytes {s.memory_usage(deep=True, index=False).sum()}')
# Initial df bytes 180
s = s.assign(s=s.s.astype('string[pyarrow]'))
print(f'pyarrow string df bytes {s.memory_usage(deep=True, index=False).sum()}')
# pyarrow string df bytes 25
s.to_feather('s.feather')
s = pd.read_feather('s.feather')
print(f'after feather bytes {s.memory_usage(deep=True, index=False).sum()}')
# after feather bytes 180
```


### Issue Description

Loading a df that contains a column of type string[pyarrow] from a feather file loads the column as type string

### Expected Behavior

Load the column in its original string[pyarrow] type

### Installed Versions

<details>

INSTALLED VERSIONS
------------------
commit           : 5f648bf1706dd75a9ca0d29f26eadfbb595fe52b
python           : 3.9.6.final.0
python-bits      : 64
OS               : Darwin
OS-release       : 20.4.0
Version          : Darwin Kernel Version 20.4.0: Thu Apr 22 21:46:47 PDT 2021; root:xnu-7195.101.2~1/RELEASE_X86_64
machine          : x86_64
processor        : i386
byteorder        : little
LC_ALL           : None
LANG             : None
LOCALE           : None.UTF-8

pandas           : 1.3.2
numpy            : 1.21.2
pytz             : 2021.1
dateutil         : 2.8.2
pip              : 21.2.4
setuptools       : 52.0.0.post20210125
Cython           : None
pytest           : None
hypothesis       : None
sphinx           : None
blosc            : None
feather          : None
xlsxwriter       : None
lxml.etree       : None
html5lib         : None
pymysql          : None
psycopg2         : None
jinja2           : 3.0.1
IPython          : 7.27.0
pandas_datareader: None
bs4              : None
bottleneck       : None
fsspec           : 2021.08.1
fastparquet      : None
gcsfs            : 2021.08.1
matplotlib       : 3.4.3
numexpr          : None
odfpy            : None
openpyxl         : None
pandas_gbq       : None
pyarrow          : 5.0.0
pyxlsb           : None
s3fs             : None
scipy            : 1.7.1
sqlalchemy       : 1.4.23
tables           : None
tabulate         : None
xarray           : None
xlrd             : None
xlwt             : None
numba            : None


</details>
