ci: add flake8 and black configuration

Author: JulianFeinauer

.flake8

@@ -0,0 +1,17 @@
+[flake8]
+ignore =
+    E402,
+    E203,
+    W503
+max-line-length = 300
+exclude =
+    .git,
+    test*.py,
+    tools/*
+extend-exclude =
+    dist,
+    build,
+    venv
+show-source = True
+statistics = True
+format = %(path)s:%(row)d,%(col)d:%(code)s:%(text)s:https://lintlyci.github.io/Flake8Rules/rules/%(code)s.html

pyproject.toml

@@ -4,3 +4,31 @@ requires = [
     "setuptools_scm >= 2.0.0, <3"
 ]
 build-backend = "setuptools.build_meta"
+
+[tool.black]
+line-length = 88
+target-version = ['py37']
+include = '\.pyi?$'
+exclude = '''
+
+(
+  /(
+      \.eggs         # exclude a few common directories in the
+    | \.git          # root of the project
+    | \.hg
+    | \.mypy_cache
+    | \.tox
+    | \.venv
+    | venv
+    | _build
+    | buck-out
+    | build
+    | dist
+    | migrations
+    | packages
+    | \tools
+  )/
+  | foo.py           # also separately exclude a file named foo.py in
+                     # the root of the project
+)
+'''