Create requests-async based TestClient, remove aiohttp dependency, drop Python 3.5

Update all tests to be compatible with requests-async
Cleanup testing client changes with black and isort
Remove Python 3.5 and other meta doc cleanup
rename pyproject and fix pep517 error
Add black config to tox.ini
Cleanup tests and remove aiohttp
tox.ini change for easier development commands
Remove aiohttp from changelog and requirements
Cleanup imports and Makefile

tests/test_response.py

@@ -1,6 +1,7 @@
 import asyncio
 import inspect
 import os
+
 from collections import namedtuple
 from mimetypes import guess_type
 from random import choice
@@ -8,6 +9,7 @@ from unittest.mock import MagicMock
 from urllib.parse import unquote
 
 import pytest
+
 from aiofiles import os as async_os
 
 from sanic.response import (
@@ -18,11 +20,11 @@ from sanic.response import (
     json,
     raw,
     stream,
-    text,
 )
 from sanic.server import HttpProtocol
 from sanic.testing import HOST, PORT
 
+
 JSON_DATA = {"ok": True}
 
 
@@ -77,10 +79,10 @@ def test_response_header(app):
 
     request, response = app.test_client.get("/")
     assert dict(response.headers) == {
-        "Connection": "keep-alive",
-        "Keep-Alive": str(app.config.KEEP_ALIVE_TIMEOUT),
-        "Content-Length": "11",
-        "Content-Type": "application/json",
+        "connection": "keep-alive",
+        "keep-alive": str(app.config.KEEP_ALIVE_TIMEOUT),
+        "content-length": "11",
+        "content-type": "application/json",
     }
 
 
@@ -276,7 +278,7 @@ def test_stream_response_with_cookies(app):
         return response
 
     request, response = app.test_client.get("/")
-    assert response.cookies["test"].value == "pass"
+    assert response.cookies["test"] == "pass"
 
 
 def test_stream_response_without_cookies(app):