"Unknown error code '125'" during file conversion on Windows

[apyrgio]

A Windows user has reported that they got the following error message in the Dangerzone UI, while converting a file:

Unknown error code '125'

Most likely, Docker Desktop returned this error code due to a configuration issue. A quick search shows that probably file sharing restrictions are in play here:

• https://forums.docker.com/t/filesharing-not-enabled-volume-sharing-is-not-enabled-on-the-settings-screen-in-docker-desktop-error-125/95332

A temporary solution seems to be to go to the "File Sharing" tab of Docker Desktop, and add the path of the files, so that they can be mounted. A better solution is to fix #443, which is long overdue.