chore: switch to node 20

.github/workflows/ci.yaml

@@ -14,21 +14,16 @@ jobs:
     runs-on: ubuntu-latest
     env:
       CI: true
-    strategy:
-      matrix:
-        node-version: [14.x, 16.x, 18.x]
-    name: Use Node.js ${{ matrix.node-version }}
+    name: Test and lint
     steps:
       - uses: actions/checkout@v3
       - name: Setup node
         uses: actions/setup-node@v3
         with:
-          node-version: ${{ matrix.node-version }}
+          node-version: 20.x
       - name: npm install
         run: npm i
       - name: Unittesting
         run: npm run test
       - name: Linting
-        # Only test on one version to avoid duplicate linter annotations.
-        if: ${{ matrix.node-version == '16.x' }}
         run: npm run lint