ci: Use only Node.js 20.x in CI workflow

.github/workflows/ci.yml

@@ -9,27 +9,24 @@ on:
 jobs:
   build:
     runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        node-version: [18.x, 20.x]
 
     steps:
-    - uses: actions/checkout@v3
-
-    - name: Use Node.js ${{ matrix.node-version }}
-      uses: actions/setup-node@v3
-      with:
-        node-version: ${{ matrix.node-version }}
-        cache: 'npm'
-
-    - name: Install dependencies
-      run: npm ci
-
-    - name: Build
-      run: npm run build
+      - uses: actions/checkout@v3
 
-    - name: Lint
-      run: npm run lint
+      - name: Use Node.js
+        uses: actions/setup-node@v3
+        with:
+          node-version: '20.x'
+          cache: 'npm'
 
-    - name: Test
-      run: npm test
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Build
+        run: npm run build
+
+      - name: Lint
+        run: npm run lint
+
+      - name: Test
+        run: npm test