Upgrade actions/setup-node from v3 to v4.

This should address a warning our builds have been getting[^1]:

> The following actions use a deprecated Node.js version and will be forced to run on node20: actions/setup-node@v3. For more info:
> https://github.blog/changelog/2024-03-07-github-actions-all-actions-will-run-on-node20-instead-of-node16-by-default/

[^1]: https://github.com/block/elasticgraph/actions/runs/11565680928

.github/workflows/ci.yaml

@@ -54,7 +54,7 @@ jobs:
           ruby-version: ${{ matrix.ruby }}
           bundler-cache: true # runs 'bundle install' and caches installed gems automatically
 
-      - uses: actions/setup-node@v3
+      - uses: actions/setup-node@v4
         with:
           node-version: "23.x"
 

script/update_ci_yaml

@@ -136,7 +136,7 @@ jobs:
           ruby-version: ${{ matrix.ruby }}
           bundler-cache: true # runs 'bundle install' and caches installed gems automatically
 
-      - uses: actions/setup-node@v3
+      - uses: actions/setup-node@v4
         with:
           node-version: "23.x"