chore(actions): run docs actions on Node 16 to conform with the project (#26868)

Co-authored-by: Maxime Beauchemin <maximebeauchemin@gmail.com>

.github/workflows/superset-docs-deploy.yml

@@ -25,7 +25,7 @@ jobs:
     needs: config
     if: needs.config.outputs.has-secrets
     name: Build & Deploy
-    runs-on: ubuntu-20.04
+    runs-on: "ubuntu-latest"
     defaults:
       run:
         working-directory: docs
@@ -35,6 +35,10 @@ jobs:
         with:
           persist-credentials: false
           submodules: recursive
+      - name: Set up Node.js 16
+        uses: actions/setup-node@v2
+        with:
+          node-version: '16'
       - name: yarn install
         run: |
           yarn install --check-cache