add pkg.pr.new to publish pr releases (#12061)

Author: phryneas

.github/workflows/publish-pr-releases.yml

@@ -0,0 +1,28 @@
+name: Pull Request Prerelease
+
+on:
+  pull_request:
+  push:
+    branches:
+      - "**"
+    tags:
+      - "!**"
+
+jobs:
+  prerelease:
+    name: Pull Request Prerelease
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repo
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js 20.x
+        uses: actions/setup-node@v4
+        with:
+          node-version: 20.x
+
+      - name: Install dependencies with cache
+        uses: bahmutov/npm-install@v1
+
+      - name: Build and publish to pkg.pr.new
+        run: npm run pkg-pr-new-publish