For djvu preview, convert from tiff to jpg

[8vasu]

ISSUE TYPE

• Bug fix

RUNTIME ENVIRONMENT

• Operating system and version: Debian 12 (also previously Debian 11 with a different Python version)
• Terminal emulator and version: uxterm with $XTERM_VERSION = XTerm(379) and $TERM = tmux-256color
• ranger version: ranger 1.9.3
• Python version: 3.11.2 (main, Mar 13 2023, 12:18:29) [GCC 12.2.0]
• Locale: en_US.UTF-8

CHECKLIST

• The CONTRIBUTING document has been read [REQUIRED]
• All changes follow the code style [REQUIRED]
• All new and existing tests pass [REQUIRED]
• Changes require config files to be updated
  • Config files have been updated
• Changes require documentation to be updated
  • Documentation has been updated
• Changes require tests to be updated
  • Tests have been updated

DESCRIPTION

In the djvu image preview section in scope.sh, now we create a temporary tiff file, convert it to jpg, and then delete the temporary tiff file.

MOTIVATION AND CONTEXT

On my Debian 11 system (upgraded just yesterday to Debian 12), Djvu previews were not working. I verified that the ddjvu(1) command was able to produce a valid tiff file. Therefore, w3mimgdisplay must have not been able to read the tiff file. Upon adding a single line of convert(1), the tiff file is converted to jpg, and that solves the problem.

TESTING

IMAGES / VIDEOS

Edit: added $TERM value.