Upgrade GH actions to reduce CI warnings (#7403)

Deals with one of the warnings GH shows on our actions run:

https://github.com/zed-industries/zed/actions/runs/7790218555
<img width="1383" alt="image"
src="https://github.com/zed-industries/zed/assets/2690773/e523ec7c-bf43-4b0d-8c36-8540aef6fae9">

bufbuild/* actions seem to have no new major versions so there's nothing
new to upgrade to.

Release Notes:

- N/A

.github/actions/run_tests/action.yml

@@ -10,7 +10,7 @@ runs:
               cargo install cargo-nextest
 
         - name: Install Node
-          uses: actions/setup-node@v3
+          uses: actions/setup-node@v4
           with:
               node-version: "18"