IntFlag Enum - broken after py3.11

Hi!
cloudpickling for IntFlag Enum seems to be broken after python 3.11

cloudpickle version : 3.1.1

Test Code

```python

import enum
import cloudpickle
import pickle
import sys
print(sys.version)

class EnumClass(enum.Enum):
RANK_0 = 11
RANK_1 = 37
RANK_2 = 389

class IntFlagClass(enum.IntFlag):
RANK_0 = 11
RANK_1 = 37
RANK_2 = 389

def test(pickler, value):
print(f"testing {pickler} for {value} ... ", end="")

pickled = pickler.dumps(value)
unpickled = pickler.loads(pickled)
assert(unpickled == value)

print(f" success.")

for mod in [pickle, cloudpickle]:
for val in [EnumClass.RANK_1, IntFlagClass.RANK_1]:
test(mod, val)
```

Results for python 3.8 to 3.10, which is fine

```bash
3.8.20 (default, Oct 3 2024, 10:22:23)
[Clang 14.0.6 ]
testing for EnumClass.RANK_1 ... success.
testing for 37 ... success.
testing for EnumClass.RANK_1 ... success.
testing for 37 ... success.

3.9.21 (main, Dec 11 2024, 10:21:40)
[Clang 14.0.6 ]
testing for EnumClass.RANK_1 ... success.
testing for 37 ... success.
testing for EnumClass.RANK_1 ... success.
testing for 37 ... success.

3.10.16 (main, Dec 11 2024, 10:22:29) [Clang 14.0.6 ]
testing for EnumClass.RANK_1 ... success.
testing for 37 ... success.
testing for EnumClass.RANK_1 ... success.
testing for 37 ... success.
```

We get same error for python 3.11 to 3.13

``` bash
3.11.11 (main, Dec 11 2024, 10:25:04) [Clang 14.0.6 ]
testing for EnumClass.RANK_1 ... success.
testing for 37 ... success.
testing for EnumClass.RANK_1 ... success.
testing for 37 ... Traceback (most recent call last):
File "/Users/ekrem/Desktop/work/test/pickle_test.py", line 30, in
test(mod, val)
File "/Users/ekrem/Desktop/work/test/pickle_test.py", line 23, in test
unpickled = pickler.loads(pickled)
^^^^^^^^^^^^^^^^^^^^^^
File "~/test/py3.11/lib/python3.11/site-packages/cloudpickle/cloudpickle.py", line 1177, in _class_setstate
setattr(obj, attrname, attr)
File "~/test/py3.11/lib/python3.11/enum.py", line 838, in __setattr__
raise AttributeError('cannot reassign member %r' % (name, ))
AttributeError: cannot reassign member 'RANK_0'

3.12.9 | packaged by Anaconda, Inc. | (main, Feb 6 2025, 12:55:12) [Clang 14.0.6 ]
testing for EnumClass.RANK_1 ... success.
testing for 37 ... success.
testing for EnumClass.RANK_1 ... success.
testing for 37 ... Traceback (most recent call last):
File "/Users/ekrem/Desktop/work/test/pickle_test.py", line 30, in
test(mod, val)
File "/Users/ekrem/Desktop/work/test/pickle_test.py", line 23, in test
unpickled = pickler.loads(pickled)
^^^^^^^^^^^^^^^^^^^^^^
File "~/test/py3.12/lib/python3.12/site-packages/cloudpickle/cloudpickle.py", line 1177, in _class_setstate
setattr(obj, attrname, attr)
File "~/test/py3.12/lib/python3.12/enum.py", line 854, in __setattr__
raise AttributeError('cannot reassign member %r' % (name, ))
AttributeError: cannot reassign member 'RANK_0'

3.13.2 | packaged by Anaconda, Inc. | (main, Feb 6 2025, 12:55:35) [Clang 14.0.6 ]
testing for EnumClass.RANK_1 ... success.
testing for 37 ... success.
testing for EnumClass.RANK_1 ... success.
testing for 37 ... Traceback (most recent call last):
File "/Users/ekrem/Desktop/work/test/pickle_test.py", line 30, in
test(mod, val)
~~~~^^^^^^^^^^
File "/Users/ekrem/Desktop/work/test/pickle_test.py", line 23, in test
unpickled = pickler.loads(pickled)
File "~/test/py3.13/lib/python3.13/site-packages/cloudpickle/cloudpickle.py", line 1177, in _class_setstate
setattr(obj, attrname, attr)
~~~~~~~^^^^^^^^^^^^^^^^^^^^^
File "~/test/py3.13/lib/python3.13/enum.py", line 835, in __setattr__
raise AttributeError('cannot reassign member %r' % (name, ))
AttributeError: cannot reassign member 'RANK_0'
```