Add staging workflow

.github/workflows/publish-staging.yml

@@ -0,0 +1,15 @@
+name: Publish Staging
+
+on:
+  workflow_dispatch:
+
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    name: Deploy
+    steps:
+      - uses: actions/checkout@master
+      - name: Publish
+        env:
+          CF_API_TOKEN: ${{ secrets.CF_API_TOKEN }}
+        run: npm install -g wrangler && wrangler publish --env staging