Release new version (with fixes for pickling)?

Hey folks,

Recent versions of frozenlist seem to not be pickleable. The latest version on pypi is 1.7.0:

```
In [1]: import frozenlist

In [2]: import pickle

In [3]: f = frozenlist.FrozenList([1,2])

In [4]: pickle.loads(pickle.dumps(f))
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
Cell In[4], line 1
----> 1 pickle.loads(pickle.dumps(f))

File :2, in frozenlist._frozenlist.FrozenList.__reduce_cython__()

TypeError: self._frozen cannot be converted to a Python object for pickling

In [5]: frozenlist.__version__
Out[5]: '1.7.0'
```

.. so we fail to pickle on 1.7.0.

However on the latest git hash: d973b7a74488196b174df4d24ad15424900f8d43, it seems to work just fine:
```
In [1]: import pickle

In [2]: import frozenlist

In [3]: f = frozenlist.FrozenList([1,2])

In [4]: pickle.loads(pickle.dumps(f))
Out[4]:

In [5]: f.freeze()

In [6]: pickle.loads(pickle.dumps(f))
Out[6]:

In [7]: frozenlist.__version__
Out[7]: '1.7.1.dev0'
```

Can there be a new release to pypi that has this fixed? Thanks!