Update multidict to 4.7.2

[pyup-bot]

This PR updates multidict from 4.6.1 to 4.7.2.

Changelog

4.7.2

==================

Bugfixes
--------

- Fix crashing when multidict is used pyinstaller
`432 <https://github.com/aio-libs/multidict/issues/432>`_
- Fix typing for `CIMultiDict.copy`
`434 <https://github.com/aio-libs/multidict/issues/434>`_
- Fix memory leak in ``MultiDict.copy()``
`443 <https://github.com/aio-libs/multidict/issues/443>`_


----

4.7.1

==================

Bugfixes
--------

- `CIMultiDictProxy.copy` return object type `multidict._multidict.CIMultiDict`
`427 <https://github.com/aio-libs/multidict/issues/427>`_
- Make `CIMultiDict` subclassable again
`416 <https://github.com/aio-libs/multidict/issues/416>`_
- Fix regression, multidict can be constructed from arbitrary iterable of pairs again.
`418 <https://github.com/aio-libs/multidict/issues/418>`_
- `CIMultiDict.add` may be called with keyword arguments
`421 <https://github.com/aio-libs/multidict/issues/421>`_


Improved Documentation
----------------------

- Mention ``MULTIDICT_NO_EXTENSIONS`` environment variable in docs.
`393 <https://github.com/aio-libs/multidict/issues/393>`_
- Document the fact that ``istr`` preserves the casing of argument untouched but uses internal lower-cased copy for keys comparison.
`419 <https://github.com/aio-libs/multidict/issues/419>`_


----

4.7.0

==================

Features
--------

- Replace Cython optimization with pure C
`249 <https://github.com/aio-libs/multidict/issues/249>`_
- Implement ``__length_hint__()`` for iterators
`310 <https://github.com/aio-libs/multidict/issues/310>`_
- Support the MultiDict[str] generic specialization in the runtime.
`392 <https://github.com/aio-libs/multidict/issues/392>`_
- Embed pair_list_t structure into MultiDict Python object
`395 <https://github.com/aio-libs/multidict/issues/395>`_
- Embed multidict pairs for small dictionaries to amortize the memory usage.
`396 <https://github.com/aio-libs/multidict/issues/396>`_
- Support weak references to C Extension classes.
`399 <https://github.com/aio-libs/multidict/issues/399>`_
- Add docstrings to provided classes.
`400 <https://github.com/aio-libs/multidict/issues/400>`_
- Merge ``multidict._istr`` back with ``multidict._multidict``.
`409 <https://github.com/aio-libs/multidict/issues/409>`_


Bugfixes
--------

- Explicitly call ``tp_free`` slot on deallocation.
`407 <https://github.com/aio-libs/multidict/issues/407>`_
- Return class from __class_getitem__ to simplify subclassing
`413 <https://github.com/aio-libs/multidict/issues/413>`_


----

Links

• PyPI: https://pypi.org/project/multidict
• Changelog: https://pyup.io/changelogs/multidict/
• Repo: https://github.com/aio-libs/multidict

[pyup-bot]

Closing this in favor of #104