Switch CI from Travis to GitHub Actions (#41)

Fix #39.
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
new file mode 100644
index 0000000..470c010
--- /dev/null
+++ b/.github/workflows/test.yml
@@ -0,0 +1,70 @@
+name: test
+
+on:
+  push:
+    branches:
+      - master
+      - "test-me-*"
+    tags:
+      - "*"
+  pull_request:
+    branches:
+      - master
+
+# Set permissions at the job level.
+permissions: {}
+
+jobs:
+  lint:
+    runs-on: ubuntu-20.04
+    timeout-minutes: 10
+    permissions:
+      contents: read
+
+    steps:
+    - uses: actions/checkout@v3
+
+    - uses: actions/setup-python@v4
+      with:
+        python-version: 3.11
+
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install tox
+
+    - name: Lint
+      run: tox -e lint
+
+  test:
+    runs-on: ubuntu-20.04
+    timeout-minutes: 10
+    permissions:
+      contents: read
+
+    strategy:
+      fail-fast: false
+      matrix:
+        python: [
+          "3.7.1",
+          "3.7",
+          "3.8",
+          "3.9",
+          "3.10",
+          "3.11",
+        ]
+
+    steps:
+    - uses: actions/checkout@v3
+
+    - uses: actions/setup-python@v4
+      with:
+        python-version: ${{ matrix.python }}
+
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install tox
+
+    - name: Test
+      run: tox -e py
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index f1f4b7b..0000000
--- a/.travis.yml
+++ /dev/null
@@ -1,45 +0,0 @@
-language: python
-# cache package wheels (1 cache per python version)
-cache: pip
-# newer python versions are available only on xenial (while some older only on trusty) Ubuntu distribution
-dist: trusty
-
-env:
-  TOXENV=py
-
-jobs:
-  include:
-  - python: 3.5.0
-  - python: 3.5.1
-  - python: 3.5.2
-  - python: 3.5.3
-  - python: 3.5
-  - python: 3.6.0
-  - python: 3.6.1
-  - python: 3.6.2
-  - python: 3.6
-    dist: xenial
-  - python: 3.7.0
-    dist: xenial
-  - python: 3.7.1
-    dist: xenial
-  - python: 3.7
-    dist: xenial
-  - python: 3.8
-    dist: xenial
-  - python: 3.9
-    dist: xenial
-
-  - name: "check code style with flake8"
-    python: 3.7
-    dist: xenial
-    env:
-    - TOXENV=lint
-
-install:
-- pip install -U pip setuptools
-- pip install -U tox
-- tox --notest
-
-script:
-- tox
diff --git a/tox.ini b/tox.ini
index 0a61ca8..9f64a32 100644
--- a/tox.ini
+++ b/tox.ini
@@ -9,7 +9,7 @@
 
 [testenv:lint]
 description = check the code style
-basepython = python3.7
+basepython = python3
 deps = flake8
 commands = flake8 -j0 {posargs}