fix: update GitHub Actions workflow to set up Xvfb for testing

Author: dermatz

.github/workflows/test.yml

@@ -20,17 +20,17 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v2
-
-      - name: Set up Node.js
-        uses: actions/setup-node@v2
-        with:
-          node-version: ${{ matrix.node-version }}
-
+      - name: Set up Xvfb
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y xvfb
+          Xvfb :99 -screen 0 1024x768x24 &
+          export DISPLAY=:99
+      - name: Checkout code
+        uses: actions/checkout@v2
       - name: Install dependencies
         run: npm install
-
       - name: Compile the extension
         run: npm run compile
-
       - name: Run tests
         run: npm test