Add explicit Python installation

.github/workflows/test.yaml

@@ -24,6 +24,10 @@ jobs:
         node-version-file: '.nvmrc'
         cache: 'npm'
         cache-dependency-path: package-lock.json
+    - name: Set up Python
+      uses: actions/setup-python@v2
+      with:
+        python-version: '3.8'
     - name: Install dependencies
       run: npm ci
     - name: Generate coverage report