Do not build on Windows and add missing packages for Python 3.6

appveyor.yml

@@ -1,21 +0,0 @@
-version: '{build}-{branch}'
-
-image: Visual Studio 2015
-
-platform: x64
-
-environment:
-    PYTHON: "C:\\Python36-x64"
-    DISTUTILS_USE_SDK: "1"
-    API_TOKEN:
-        secure: VEKn4bYH3QO0ixtQW5ni4Enmn8cS1NlZV246ludBDgQ=
-
-install:
-   - cinst nmap
-   - "%PYTHON%\\python.exe -m pip install -r dev-requirements.txt"
-   - "%PYTHON%\\python.exe -m pip install -r win-requirements.txt"
-
-build: off
-
-test_script:
-    - "%PYTHON%\\python.exe -m pytest -v"

requirements.txt

@@ -14,3 +14,5 @@ sqlalchemy==1.4.0b1  # beta version with asyncio support
 passlib[bcrypt]==1.7.2
 python-jose==3.2.0
 email-validator==1.1.2
+async-exit-stack==1.0.1  ; python_version < "3.7"
+async-generator==1.10  ; python_version < "3.7"