Add stickler and black config files

Author: uvchik

.stickler.yml

@@ -0,0 +1,13 @@
+linters:
+    flake8:
+      python: 3
+    black:
+      config: ./pyproject.toml
+      fixer: true:
+
+files:
+    ignore:
+        - 'src/generated/*'
+
+fixers:
+    enable: true

pyproject.toml

@@ -0,0 +1,18 @@
+[tool.black]
+line-length = 88
+target-version = ['py36', 'py37', 'py38']
+include = '\.pyi?$'
+exclude = '''
+/(
+    \.eggs
+  | \.git
+  | \.hg
+  | \.mypy_cache
+  | \.tox
+  | \.venv
+  | _build
+  | buck-out
+  | build
+  | dist
+)/
+'''