Describe the bug

OCRmyPDF did not produce any output for file [...]

System

• App version: 1.30.1
• Nextcloud version: 30.0.5
• PHP version: 8.2.27
• Environment: native PHP-FPM + Caddy
• ocrmypdf version: 14.0.1+dfsg1

How to reproduce

Steps to reproduce the behavior:

1. Take a screenshot with Windows Snipping tool
2. Upload it to Nextcloud with matching rules for OCR workflow
3. See error

Server log

OCRmyPDF succeeded with warning(s): The input image has an alpha channel. Remove the alpha channel first.\nUnsupportedImageFormatError
OCRmyPDF did not produce any output for file [...]

Additional context

Same error happens if I use ocrmypdf directly with this image.
Afaik the alpha channel is totally useless here as it's just a basic screenshot.
Could we remove it before running ocrmypdf?