Also move thumbnail when ytarchiver downloads it

[giannoug]

When you supply the --write-thumbnail parameter to ytarchiver, the downloaded thumbnail isn't moved along with the video file. It stays inside the temp folder.

Example config:

[ytarchive]
executable_path = "ytarchive"
working_directory = "temp"
args = [
  "--vp9", "--thumbnail", "--add-metadata", "--threads", "4",
  "--retry-stream", "30",
  "--no-frag-files", "--thumbnail", "--write-thumbnail",
  "--output", "%(upload_date)s %(title)s [%(channel)s] (%(id)s)"
]
quality = "best"
# Delay between starting ytarchive processes. Increase this number if you get
# rate limited by YouTube.
delay_start = "1s"

[AlphaCentauri]

Would love to see this fixed as well. Just wanted to also add that this happens to any extra files ytarchive creates. (thumbnails, description files, etc.) It only moves the video file after the finishing the download.