Added GitHub action to start preview app.

.github/workflows/fly_pr_preview.yml

@@ -0,0 +1,34 @@
+name: Start preview app
+
+on:
+  pull_request:
+    types: [labeled, synchronize, opened, reopened, close]
+    paths-ignore:
+      - 'docs/**'
+
+concurrency:
+  group: ${{ github.workflow }}-pr-${{ github.event.number }}
+  cancel-in-progress: true
+
+permissions:
+   contents: read
+
+env:
+    FLY_API_TOKEN: ${{ secrets.FLY_API_TOKEN }}
+    FLY_REGION: waw
+    FLY_ORG: personal
+
+jobs:
+  preview-app:
+    if: contains(github.event.pull_request.labels.*.name, 'PR preview app')
+    runs-on: ubuntu-latest
+    name: Preview app
+    environment:
+      name: pr-${{github.event.number }}
+      url: ${{ steps.deploy.outputs.url }}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Deploy preview app
+        uses: superfly/[email protected]
+        id: deploy 

django/views/templates/default_urlconf.html

@@ -218,6 +218,7 @@
           <path class="flame" d="M250.27 178.834l-5.32-8.93s-2.47-5.7 3.458-6.118h10.26s6.232.266 3.306 6.194l-5.244 8.93s-3.23 4.37-6.46 0v-.076z" fill="#AA2247"/>
         </svg>
         <h1>{% translate "The install worked successfully! Congratulations!" %}</h1>
+        <h2>🎈 This is PR preview app, started on Fly.io 🎈<h2>
         <p>{% blocktranslate %}You are seeing this page because <a href="https://docs.djangoproject.com/en/{{ version }}/ref/settings/#debug" target="_blank" rel="noopener">DEBUG=True</a> is in your settings file and you have not configured any URLs.{% endblocktranslate %}</p>
       </main>
       <footer>