Update the libvips to 18.15.1

[yash-learner]

Describe the bug
Look like by default the libvips installed on Debian machines is not the latest, so update the docker configuration to use version >= 18.15.1 to fix the issue of saving jfif images

on development, install libvips >= 18.15.1 and update the docs.

Vips::Error: VipsForeignSave: "/tmp/image_processingjfif" is not a known file format
VipsForeignSave: "/tmp/image_processing.jfif" is not a known file format

To Reproduce
Steps to reproduce the behavior:

1. Upload an image with jfif as user avatar
2. This would cause a crash error 500 on all the pages the user avatar is rendered.

Additional context

• VipsForeignSave: jfif is not a known file format libvips/libvips#3775 (comment)
• [ActiveStorage] Fix JFIF issue with VIPS processor rails/rails#50175