ci: add publish.yml

.github/workflows/publish.yml

+name: Publish
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  publish:
+    runs-on: ubuntu-latest
+
+    permissions:
+      contents: read
+      id-token: write
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Publish @llamaindex/env
+        run: npx jsr publish
+        working-directory: packages/env
+
+      - name: Publish @llamaindex/core
+        run: npx jsr publish
+        working-directory: packages/core