trivial: Bump hacking to 4.x

We also remove a now-useless requirement from 'test-requirements' since
that stuff is handled by pre-commit.

Signed-off-by: Stephen Finucane <stephenfin@redhat.com>
Change-Id: I324251c28f9fd6b61909e5288974b96f804ec19d

.pre-commit-config.yaml

@@ -28,8 +28,8 @@ repos:
       - id: check-yaml
         files: .*\.(yaml|yml)$
   - repo: https://gitlab.com/pycqa/flake8
-    rev: ee2920d775df18481d638c2da084d229d56f95b9  # 3.7.9
+    rev: fb91b994ed4adf4f2b4890e7bdba82f57e3a81df  # 3.8.4
     hooks:
       - id: flake8
         additional_dependencies:
-          - hacking>=3.0.1,<3.1.0
+          - hacking>=4.0.0,<4.1.0

test-requirements.txt

@@ -2,8 +2,6 @@
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
 
-hacking>=3.0,<3.1.0 # Apache-2.0
-
 # Used for making sure the eventlet executors work.
 eventlet!=0.18.3,!=0.20.1,>=0.18.2 # MIT