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_utils
Also add the pyupgrade hook to pre-commit to avoid merging additional
Python 2 syntaxes.
Change-Id: If34f08dc3156b75f38dfe1c5e4698952fea7abba
41f5fb6e00