ci(test): use Node 16 in test job

Author: gr2m

.github/workflows/test.yml

@@ -35,10 +35,9 @@ jobs:
     needs: test_matrix
     steps:
       - uses: actions/checkout@v2
-      - name: "Use Node.js ${{ matrix.node-version }}"
-        uses: actions/setup-node@v2
+      - uses: actions/setup-node@v2
         with:
-          node-version: "${{ matrix.node-version }}"
+          node-version: 16
           cache: npm
       - run: npm ci
       - run: npm run lint