changedetection.io vulnerable to unauthenticated static path traversal

changedetection.io is a free open source web page change detection tool. In versions prior to 0.53.2, the `/static/<group>/<filename>` route accepts `group=".."`, which causes `send_from_directory("static/..", filename)` to execute. This moves the base directory up to `/app/changedetectionio`, enabling unauthenticated local file read of application source files (e.g., `flask_app.py`). Version 0.53.2 fixes the issue.