Add Python 3.11 support (#1284)

Author: seratch

.github/workflows/ci-build.yml

@@ -12,10 +12,7 @@ jobs:
     timeout-minutes: 10
     strategy:
       matrix:
-        # TODO: 3.10 in GH Actions is not yet stable enough for us
-        # You may often encounter "Error: Process completed with exit code 250."
-        # python-version: ['3.6', '3.7', '3.8', '3.9', '3.10']
-        python-version: ['3.6', '3.7', '3.8', '3.9']
+        python-version: ['3.6', '3.7', '3.8', '3.9', '3.10', '3.11']
     env:
       PYTHON_SLACK_SDK_MOCK_SERVER_MODE: 'threading'
       #CI_UNSTABLE_TESTS_SKIP_ENABLED: '1'

setup.py

@@ -305,6 +305,7 @@ def run(self):
         "Programming Language :: Python :: 3.8",
         "Programming Language :: Python :: 3.9",
         "Programming Language :: Python :: 3.10",
+        "Programming Language :: Python :: 3.11",
     ],
     keywords="slack slack-api web-api slack-rtm websocket chat chatbot chatops",
     packages=find_packages(