Client.write_data default value {} should be changed

[briantist]

hvac/hvac/v1/__init__.py

Line 351 in ede8622

data: t.Dict[str, t.Any] = {},

https://pylint.pycqa.org/en/latest/user_guide/messages/warning/dangerous-default-value.html

It seems this default was a bad idea.

As far as I know, all the code this value will go through will not mutate the value, but we should fix this before that situation changes.

I think we'll be able to default it to None and everything will still work correctly even if we pass it to post that way; worst case it doesn't and we default to {} inside the function if it's None.

Either way this change won't be breaking and will prevent future pain, breakage, and surprise.

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I found this in a downstream project that uses pylint. It raises the question of whether we should maybe be using pylint, or perhaps #1059 would have caught it as well?