Add CI workflow

.github/workflows/ci.yml

@@ -0,0 +1,25 @@
+name: Python CI
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up Python
+      uses: actions/setup-python@v2
+      with:
+        python-version: '3.8'
+    - name: Install dependencies
+      run: |
+        pip install -r requirements.txt
+    - name: Run tests
+      run: |
+        pytest tests/