Run tests on python 3.11 also (#1989)

Python 3.11 will be released soon, this enables running tests on the
latest beta to confirm that everything works correctly.

Other changes:
- Change TOXENV setup in Taskfile so it works for version strings like
  `3.11.0-beta.4`.
- Add a classifier for python 3.11

.github/workflows/validate.yaml

@@ -19,7 +19,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.7", "3.8", "3.9", "3.10"]
+        python-version: ["3.7", "3.8", "3.9", "3.10", "3.11.0-beta.4"]
         os: [ubuntu-latest, macos-latest, windows-latest]
         include:
           - python-version: "3.7"

Taskfile.yml

@@ -95,7 +95,7 @@ tasks:
           -m tox \
           {{.CLI_ARGS}}
     env:
-      TOXENV: '{{if .TOX_PYTHON_VERSION}}py{{replace "." "" .TOX_PYTHON_VERSION}}{{if .EXTENSIVE}}-extensive{{end}}{{end}}'
+      TOXENV: '{{if .TOX_PYTHON_VERSION}}py{{mustRegexReplaceAll "^([0-9]+)[.]([0-9]+).*" .TOX_PYTHON_VERSION "${1}${2}"}}{{if .EXTENSIVE}}-extensive{{end}}{{end}}'
   test:
     desc: Run tests
     cmds:

setup.py

@@ -87,6 +87,7 @@ def open_local(paths, mode="r", encoding="utf8"):
         "Programming Language :: Python :: 3.8",
         "Programming Language :: Python :: 3.9",
         "Programming Language :: Python :: 3.10",
+        "Programming Language :: Python :: 3.11",
         "License :: OSI Approved :: BSD License",
         "Topic :: Software Development :: Libraries :: Python Modules",
         "Operating System :: OS Independent",