Fix wasm-demo (#5352)

#5285 changed the NPM package
to build with latest nightly. However, latest nightly seems to be broken
(rust-std isn't found), so we should build with a nightly that we know
works.

.github/workflows/artifacts-build.yml

@@ -270,6 +270,8 @@ jobs:
       run: |
         npm -C ffi/npm ci
         npm -C tutorials/npm ci
+      env: 
+        PINNED_CI_NIGHTLY: nightly-2024-07-23
 
     - name: Run Webpack
       run: npm -C tutorials/npm run build