CI: Upgrade to Node 20

Author: fhammerschmidt

.github/workflows/ci.yml

@@ -121,7 +121,7 @@ jobs:
     - name: Use Node.js
       uses: actions/setup-node@v4
       with:
-        node-version: 16
+        node-version: 20
         registry-url: 'https://registry.npmjs.org'
 
     - run: npm ci
@@ -170,7 +170,7 @@ jobs:
     - name: Use Node.js
       uses: actions/setup-node@v4
       with:
-        node-version: 16
+        node-version: 20
         registry-url: 'https://registry.npmjs.org'
 
     - run: npm ci