Update version of node used in ci.yml

`ci.yml` specified Node version 14, which is very old; GitHub
officially deprecated version 16 in 2023 (c.f.
https://nodejs.org/en/blog/announcements/nodejs16-eol). Updating this
to use version 20.17.0, which is the current LTS version.

.github/workflows/ci.yml

@@ -329,7 +329,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version: '14.16.1'
+          node-version: '20.17.0'
       - name: Install npm
         run: check/npm ci
       - name: Check build matches the current
@@ -341,7 +341,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version: '14.16.1'
+          node-version: '20.17.0'
       - name: Install npm
         run: check/npm ci
       - name: Lint
@@ -353,7 +353,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version: '14.16.1'
+          node-version: '20.17.0'
       - name: Install npm dependencies
         run: check/npm ci
       - name: Unit tests
@@ -367,7 +367,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version: '14.16.1'
+          node-version: '20.17.0'
       - name: Install npm dependencies
         run: check/npm ci
       - name: Test