GHA: main-wasm.yml: use newer node by default (v24 LTS)

previously node20 was the default, with override to force node22 but
node24 has been out since May 2025 and is current LTS, with node26
out since May 2026 and current stable (but non-LTS).

.github/workflows/main-wasm.yml

@@ -35,12 +35,6 @@ on:
         type: boolean
         default: true
 
-# actions/upload-artifact@v5 still runs on Node.js 20. Force Node 24 to
-# silence the deprecation warning until upload-artifact ships a Node-24
-# release. Drop this once upgraded.
-env:
-  FORCE_JAVASCRIPT_ACTIONS_TO_NODE24: true
-
 permissions:
   contents: read
   packages: write
@@ -55,9 +49,9 @@ jobs:
           fetch-depth: 2
 
       - name: Set up Node.js
-        uses: actions/setup-node@v5
+        uses: actions/setup-node@v7
         with:
-          node-version: '22'
+          node-version: '24'
           registry-url: 'https://npm.pkg.github.com'
 
       - name: Install emsdk