Replace CircleCI with Github Actions.

Update dependencies and supported Python versions.

.github/workflows/python.yml

@@ -0,0 +1,23 @@
+name: CI
+on:
+  push:
+    branches: [ "master", "github_actions" ]
+  pull_request:
+    branches: [ "master", "github_actions" ]
+jobs:
+  test:
+    name: Run tests
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python: ["3.9", "3.10", "3.11", "3.12"]
+    steps:
+      - uses: actions/checkout@v4
+      - name: Setup Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python }}
+      - name: Install tox and any other packages
+        run: pip install tox
+      - name: Run tox
+        run: tox run -e lint,py

setup.cfg

@@ -11,4 +11,3 @@ max-line-length = 120
 force_single_line = true
 line_length = 120
 lines_between_types = 1
-not_skip = __init__.py

setup.py

@@ -41,10 +41,9 @@ def get_long_description():
         'Operating System :: OS Independent',
         'Programming Language :: Python',
         'Programming Language :: Python :: 3',
-        'Programming Language :: Python :: 3.7',
-        'Programming Language :: Python :: 3.8',
         'Programming Language :: Python :: 3.9',
         'Programming Language :: Python :: 3.10',
         'Programming Language :: Python :: 3.11',
+        'Programming Language :: Python :: 3.12',
     ],
 )

tox.ini

@@ -0,0 +1,22 @@
+[tox]
+requires =
+    tox>=4
+env_list = lint, py{39,310,311,312}
+
+[testenv]
+description = run unit tests
+deps =
+    pytest
+commands =
+    pytest {posargs:.}
+
+[testenv:lint]
+description = run linters
+skip_install = true
+deps =
+    flake8
+    flake8-commas
+    isort
+commands =
+    flake8
+    isort --check --diff .