Log Message:
py-multidict: updated to 4.7.0

4.7.0:

Features
- Replace Cython optimization with pure C
- Implement ``__length_hint__()`` for iterators
- Support the MultiDict[str] generic specialization in the runtime.
- Embed pair_list_t structure into MultiDict Python object
- Embed multidict pairs for small dictionaries to amortize the memory usage.
- Support weak references to C Extension classes.
- Add docstrings to provided classes.
- Merge ``multidict._istr`` back with ``multidict._multidict``.

Bugfixes
- Explicitly call ``tp_free`` slot on deallocation.
- Return class from __class_getitem__ to simplify subclassing