Migrate to GitHub Actions

One thing at a time. The linting will be done later with pre-commit.

.github/workflows/main.yaml

@@ -0,0 +1,52 @@
+name: Build
+on:
+  push:
+    branches:
+      - master
+
+  pull_request:
+    branches:
+      - master
+
+jobs:
+  test:
+    strategy:
+      matrix:
+        python-version:
+          - "3.7"
+          - "3.8"
+          - "3.9"
+          - "3.10"
+        os:
+          - macos
+          - ubuntu
+          - windows
+
+    name: tests
+    runs-on: ${{ matrix.os }}-latest
+    steps:
+      - uses: actions/checkout@v3.0.2
+
+      - uses: actions/setup-python@v4.2.0
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - run: pip install .
+
+      - name: run tests
+        run: python setup.py test
+
+  fuzz:
+    name: fuzz
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3.0.2
+
+      - uses: actions/setup-python@v4.2.0
+        with:
+          python-version: "3.10"
+
+      - run: pip install .
+
+      - name: run fuzz
+        run: python test_fuzz.py ./*.py