Add support for Python 3.8 release version on all platforms

Also:
- Try adding support for 3.9-dev on Travis
- Update to running flake8 for 3.8 instead of 3.7

Author: tleonhardt

.appveyor.yml

@@ -8,11 +8,14 @@ environment:
       PYTHON_VERSION: "3.6.x"
       PYTHON_ARCH: "64"
       TOXENV: "py36"
-
     - PYTHON: "C:\\Miniconda37-x64"
       PYTHON_VERSION: "3.7.x"
       PYTHON_ARCH: "64"
       TOXENV: "py37"
+    - PYTHON: "C:\\Miniconda38-x64"
+      PYTHON_VERSION: "3.8.x"
+      PYTHON_ARCH: "64"
+      TOXENV: "py38"
 
 init:
   - "%PYTHON%/python -V"

.travis.yml

@@ -13,9 +13,13 @@ matrix:
           dist: xenial
           env: TOXENV=py37
         - os: linux
-          python: 3.8-dev
+          python: 3.8
           dist: xenial
           env: TOXENV=py38
+        - os: linux
+          python: 3.9-dev
+          dist: xenial
+          env: TOXENV=py39
         - os: linux
           python: 3.5
           env: TOXENV=docs
@@ -43,7 +47,7 @@ install:
 before_script:
   # stop the build if there are Python syntax errors or undefined names
   # exit-zero treats all errors as warnings.  The GitHub editor is 127 chars wide
-  if [[ $TOXENV == py37 ]]; then
+  if [[ $TOXENV == py38 ]]; then
     flake8 . --count --ignore=E252,W503 --max-complexity=26 --max-line-length=127 --show-source --statistics ;
   fi
 

azure-pipelines.yml

@@ -23,6 +23,9 @@ jobs:
       Python37:
         python.version: '3.7'
         TOXENV: 'py37'
+      Python38:
+        python.version: '3.8'
+        TOXENV: 'py38'
     # Increase the maxParallel value to simultaneously run the job for all versions in the matrix (max 10 for free open-source)
     maxParallel: 4
 

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = docs,py35,py36,py37,py38
+envlist = docs,py35,py36,py37,py38,py39
 
 [pytest]
 testpaths = tests