Use node v20

Author: andykswong

.github/workflows/build.yaml

@@ -11,7 +11,7 @@ jobs:
     - uses: actions/checkout@v3
     - uses: actions/setup-node@v3
       with:
-        node-version: '18'
+        node-version: '20'
     - run: npm ci --ignore-scripts
     - run: npm run build
     - run: npm test

.github/workflows/pages.yaml

@@ -11,7 +11,7 @@ jobs:
     - uses: actions/checkout@v3
     - uses: actions/setup-node@v3
       with:
-        node-version: '18'
+        node-version: '20'
     - run: npm ci --ignore-scripts
     - run: npm run build
     - run: npm run doc