Format and lint codes and fix packaging (#125)

* add: configure files (setup.py->setup.py+setup.cfg+pyproject.toml)

* add: __download_url__

* format with black and isort

* fix: flake8 section in setup.cfg

* add: E501 to flake ignore

* fix: metadata.name does not accept attr

* fix: merge __version__.py into __init__.py

* fix: flake8 errors in tests/

* fix: datetime.datetime -> datetime

* fix: banner

* fix: ignore W605 for banner

* fix: way to install deps in CI

* add: versem to setuptools

* fix: drop python<=3.6 (#126) from package and CI

waybackpy/cli.py

@@ -1,15 +1,17 @@
-import click
-import re
-import os
 import json as JSON
+import os
 import random
-import requests
+import re
 import string
-from .__version__ import __version__
-from .utils import DEFAULT_USER_AGENT
+
+import click
+import requests
+
+from . import __version__
+from .availability_api import WaybackMachineAvailabilityAPI
 from .cdx_api import WaybackMachineCDXServerAPI
 from .save_api import WaybackMachineSaveAPI
-from .availability_api import WaybackMachineAvailabilityAPI
+from .utils import DEFAULT_USER_AGENT
 from .wrapper import Url