Replace Travis + Appveyor with GitHub Actions (WIP)

.github/workflows/test.yml

@@ -0,0 +1,35 @@
+name: Test
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  test:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-18.04, windows-2019, macos-10.15]
+        python-version: [2.7, 3.5, 3.6, 3.7, pypy2, pypy3]
+        exclude:
+          - os: windows-2019
+            python-version: pypy3
+            # TODO: Remove this; see:
+            #       https://github.com/actions/setup-python/issues/151
+            #       https://github.com/tox-dev/tox/issues/1704
+            #       https://foss.heptapod.net/pypy/pypy/-/issues/3331
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v2
+      with:
+        python-version: ${{ matrix.python-version }}
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip setuptools wheel
+        python -m pip install tox tox-gh-actions==2.1.0
+    - name: Run test via Tox
+      run: tox --skip-missing-interpreters
+    - uses: codecov/codecov-action@v1

tox.ini

@@ -1,18 +1,39 @@
 [tox]
-envlist = py27, pypy, py34, py35, py36, py37, pypy3, py27-cdecimal
+envlist =
+    py27
+    py27-cdecimal
+    pypy2
+    py35
+    py36
+    py37
+    py38
+    py39
+    pypy3
 
 [testenv]
 deps =
     pytest==4.3.1;python_version<"3.5"
     pytest==6.1.2;python_version>="3.5"
     pytest-cov
-    cdecimal: m3-cdecimal
+    cdecimal: m3-cdecimal;sys_platform != 'win32'
     freezegun==0.3.12
     backports.zoneinfo;python_version>"3.6" and python_version<"3.9"
+    tzdata;sys_platform == 'win32'
 whitelist_externals = make
-commands = make clean-cldr test
+commands = make clean-cldr test-cov
 passenv = PYTHON_TEST_FLAGS
 
+[gh-actions]
+python =
+    pypy2: pypy2
+    pypy3: pypy3
+    2.7: py27
+    3.5: py35
+    3.6: py36
+    3.7: py37
+    3.8: py38
+    3.9: py39
+
 [pep8]
 ignore = E501,E731,W503