Add CI: pip install + py_compile check

.forgejo/workflows/ci.yml

@@ -0,0 +1,15 @@
+name: CI
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  check:
+    runs-on: docker
+    container:
+      image: python:3.12-slim
+    steps:
+      - uses: actions/checkout@v4
+      - run: pip install --no-cache-dir -r requirements.txt
+      - run: python -m py_compile app.py