Update all .py source files by
$ pyupgrade --py3-only $(git ls-files | grep ".py$")
to modernize the code according to Python 3 syntaxes.
pep8 errors are fixed by
$ autopep8 --select=E127,E128,E501 --max-line-length 79 -r \
--in-place oslo_messaging
and a few manual adjustments.
Also add the pyupgrade hook to pre-commit to avoid merging additional
Python 2 syntaxes.
Change-Id: I8115b7f8c5d27ce935e4422c351add4bb72e354f
34fd61bdc2