Release hacking 3.1.0

This bumps the upper version of flake8 to the latest minor version,
which also introduces a new version of pycodestyle.

Change-Id: I40967a4905490c0ad43839b4d225ae92ff2a9e4a
Signed-off-by: Stephen Finucane <sfinucan@redhat.com>

deliverables/_independent/hacking.yaml

@@ -132,5 +132,9 @@ releases:
     projects:
       - repo: openstack/hacking
         hash: d30425b3d89ed47c9e19f17062d74ed395353a4d
+  - version: 3.1.0
+    projects:
+      - repo: openstack/hacking
+        hash: e664ef421c60ade4c2557e8d7029b81ccb8478a0
 repository-settings:
   openstack/hacking: {}