Update hacking for Python3

The repo is Python 3 now, so update hacking to version 3.0 which
supports Python 3.

Fix problems found by updated hacking version.

Change-Id: I784baf9df85d2be34a8d0a024d439f34faa32e07

test-requirements.txt

@@ -2,7 +2,7 @@
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
 
-hacking>=0.12.0,!=0.13.0,<0.14  # Apache-2.0
+hacking>=3.0,<3.1.0 # Apache-2.0
 oslo.utils>=3.33.0 # Apache-2.0
 stestr>=2.1.0 # Apache-2.0
 testtools>=1.4.0 # MIT

tests/test_titles.py

@@ -88,7 +88,7 @@ class TestTitles(testtools.TestCase):
             if "http://" in line or "https://" in line:
                 continue
             # Allow lines which do not contain any whitespace
-            if re.match("\s*[^\s]+$", line):
+            if re.match(r"\s*[^\s]+$", line):
                 continue
             self.assertTrue(
                 len(line) < 80,

tox.ini

@@ -33,7 +33,7 @@ commands =
   flake8 {posargs}
 
 [flake8]
-ignore = E128
+ignore = E128,W504
 exclude = .venv,.git,.tox,doc,.eggs
 
 [testenv:move-implemented-specs]