Set bound on black dep, return lint veto powers

the most recent version of black made some changes, _and_ introduced some bugs: psf/black#1629

let's prevent an update until it's ready

.github/workflows/lint_and_format.yml

@@ -17,7 +17,7 @@ jobs:
         python -m pip install black flake8
     - name: check formatting with black
       run: |
-        python -m black --diff src scripts
+        python -m black --diff --check src scripts
     - name: lint with flake8
       run: |
         # stop the build if there are Python syntax errors or undefined names

setup.cfg

@@ -60,7 +60,7 @@ where = src
 viz =
     matplotlib>=1.5.0
 dev =
-    black>=19.0b0
+    black>=19.0b0,<20.8b0
     flake8>=3.8.0
     m2r>=0.2.0
     mypy>=0.600