Update flake8 and black configuration

- Update black to now use 120 lines
- Update flake8 to use recommended settings for black integration

pyproject.toml

@@ -0,0 +1,5 @@
+[build-system]
+requires = ["setuptools"]
+build-backend = "setuptools.build_meta"
+[tool.black]
+line-length = 120

tox.ini

@@ -17,5 +17,5 @@ deps =
 [flake8]
 exclude = .tox,env,build,cocoalib,cocoa,help,./qt/dg_rc.py,cocoa/run_template.py,./pkg
 max-line-length = 120
-ignore = E731,E203,E501,W503
-
+select = C,E,F,W,B,B950
+extend-ignore = E203, E501