Update Node.js version in deployment workflow and package configuration

- Changed Node.js version from 18 to 20 in the GitHub Actions workflow for deploying the documentation site.
- Updated the Node.js engine requirement in package.json to reflect the new version.

Author: andrewm4894

.github/workflows/deploy-docs-site.yaml

@@ -28,7 +28,7 @@ jobs:
       - name: Setup Node
         uses: actions/setup-node@v3
         with:
-          node-version: "18"
+          node-version: "20"
 
       - name: Install dependencies
         run: yarn install --frozen-lockfile