Upgrade node to 20.x in github actions

Author: Pierre-Sassoulas

.github/workflows/tests.yml

@@ -58,7 +58,7 @@ jobs:
       - name: Use Node.js
         uses: actions/setup-node@v4
         with:
-          node-version: '16.x'
+          node-version: '18.x'
       - name: Install dependencies
         run: npm ci
       - name: Run linting