Upgrade the GitHub workflow from Node 18 to Node 20 (#78)

Author: harrisont

.github/workflows/node.js.yml

@@ -24,7 +24,7 @@ jobs:
       uses: actions/setup-node@v3
       with:
         # See supported Node.js release schedule at https://nodejs.org/en/about/previous-releases#release-schedule
-        node-version: 18
+        node-version: 20
         cache: 'npm'
     - run: npm clean-install
     - run: npm run build-grammar