Python 3.8 related

Signed-off-by: Aleksei Stepanov <penguinolog@gmail.com>

.travis.yml

@@ -16,6 +16,9 @@ _python:
   - &python37
     name: "Python 3.7"
     python: "3.7"
+  - &python38
+    name: "Python 3.8"
+    python: "3.8"
 
 _helpers:
   - &install_cython pip install --upgrade Cython
@@ -106,11 +109,15 @@ jobs:
       <<: *python36
     - stage: test
       <<: *python37
+    - stage: test
+      <<: *python38
 
     - <<: *test_cythonized
       <<: *python36
     - <<: *test_cythonized
       <<: *python37
+    - <<: *test_cythonized
+      <<: *python38
 
     - stage: deploy
       # This prevents job from appearing in test plan unless commit is tagged:

test/async_api/test_subprocess.py

@@ -16,6 +16,7 @@
 import asyncio
 import logging
 import random
+import sys
 import typing
 from unittest import mock
 
@@ -199,6 +200,7 @@ def logger(mocker):
     return mocker.patch("exec_helpers.async_api.subprocess_runner.Subprocess.logger", autospec=True)
 
 
+@pytest.mark.skipif(sys.version_info >= (3, 8), reason="Python 3.8 is not supported now by asynctest")
 async def test_001_execute_async(create_subprocess_shell, logger, run_parameters) -> None:
     """Test low level API."""
     runner = exec_helpers.async_api.Subprocess()