Applying black formatting

- Fixing flake8 configuration to agree with black
- Adding black validation check to github actions

.github/workflows/packagingtest.yml

@@ -29,11 +29,12 @@ jobs:
       run: |
         python setup.py build
         pip install .
-    - name: Lint with flake8
+    - name: Lint with flake8 and check black
       run: |
-        pip install flake8
-        flake8 . --filename '*.py,*.pyx,*.pxd' --count --max-complexity=10 --max-line-length=120 --ignore=E211,E225,E226,E227,E231,E251,E261,E262,E265,E402,E999 --show-source --statistics --exclude benchmark,build,capnp/templates/module.pyx
-        flake8 . --count --max-complexity=10 --max-line-length=120 --show-source --statistics --exclude benchmark,build
+        pip install black flake8
+        flake8 . --filename '*.py,*.pyx,*.pxd' --count --show-source --statistics --exclude benchmark,build,capnp/templates/module.pyx
+        flake8 . --count --show-source --statistics --exclude benchmark,build
+        black . --check --diff --color
     - name: Packaging
       run: |
         python setup.py bdist_wheel