resp3 parser async parser incorrectly parses maps

[kristjanvalur]

Issue discovered in pr #2947

the evaulation order of key:val in {key():val() for foo in bar} dict comprehension is undefined in Python. It mostly is left-right,
but some versions, notably recent 3.7 versions, don't behave that way. It is best to use explicit ordering when reading from a stream.

This had already been fixed for non-async parsing, but in pr #2947 caused some scheduling behaviour which triggered this to happen. A fix for async has been added there.

[kristjanvalur]

I guess a standalone fix should be done as well...