Add GitHub Actions workflow for automatic Fly.io deployment

Author: kpython

.github/workflows/deploy.yml

@@ -0,0 +1,19 @@
+name: Deploy to Fly.io
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      
+      - name: Deploy to Fly.io
+        uses: superfly/flyctl-actions@master
+        with:
+          args: "deploy"
+        env:
+          FLY_AUTH_TOKEN: ${{ secrets.FLY_API_TOKEN }}