py-multidict: updated to 4.7.5

4.7.5:

Bugfixes
- Fixed creating and updating of MultiDict from a sequence of pairs and keyword arguments. Previously passing a list argument modified it inplace, and other sequences caused an error.
- Fixed comparing with mapping: an exception raised in the `__len__` method caused raising a SyntaxError.
- Fixed comparing with mapping: all exceptions raised in the `__getitem__` method were silenced.

(adam)