At the time these files were contributed there was no discussion
of the license that the authors wanted to use, but the project was
MIT licensed at the time. As such, these files deemed to be MIT licensed.
https://github.com/jbarlow83/OCRmyPDF/issues/600
These files were contributed when the project license was GPLv3. On
discussion, all known authors of these files agreed to place them
under MIT license.
See https://github.com/jbarlow83/OCRmyPDF/issues/600