Enable black tool to run as pre-commit hook

Author: bboe

.pre-commit-config.yaml

@@ -0,0 +1,8 @@
+default_language_version:
+  python: python3.7
+fail_fast: true
+repos:
+  - hooks:
+      - id: black
+    repo: https://github.com/ambv/black
+    rev: stable

setup.py

@@ -33,6 +33,7 @@
         "Programming Language :: Python :: Implementation :: CPython",
     ],
     description="Low-level communication layer for PRAW 4+.",
+    extras_require={"dev": ["pre-commit"]},
     install_requires=["requests >=2.6.0, <3.0"],
     keywords="praw reddit api",
     license="Simplified BSD License",