V4 insitute code formatting standard using Black (#1626)

 - Formats the codebase using Black (https://black.readthedocs.io/en/stable/)
 - Updates codegen logic to use black instead of yapf for code formatting
 - Adds a pre-commit hook specification for running black prior to commit
 - Adds instructions to contributing.md for setting up pre-commit.
 - Adds a circleci test case to check that formatting is valid

Author: jonmmease

_plotly_geo/__init__.py

@@ -1,3 +1,3 @@
 # https://packaging.python.org/guides/packaging-namespace-packages/
 #         pkgutil-style-namespace-packages
-__path__ = __import__('pkgutil').extend_path(__path__, __name__)
+__path__ = __import__("pkgutil").extend_path(__path__, __name__)

setup.py

@@ -4,7 +4,7 @@
 
 def readme():
     parent_dir = os.path.dirname(os.path.realpath(__file__))
-    with open(os.path.join(parent_dir, 'README.md')) as f:
+    with open(os.path.join(parent_dir, "README.md")) as f:
         return f.read()
 
 
@@ -31,8 +31,6 @@ def readme():
         "Topic :: Scientific/Engineering :: Visualization",
     ],
     license="MIT",
-    packages=[
-        "_plotly_geo",
-    ],
-    package_data={'_plotly_geo': ['package_data/*']},
+    packages=["_plotly_geo"],
+    package_data={"_plotly_geo": ["package_data/*"]},
 )