Descriptions from exif data with only whitespeces are considered empty

I noticed that pictures taken with Ubuntu-Touch have whitespace in one of the fields
This should just be ignored imo

lib/pleroma/upload/filter/exiftool/read_description.ex

@@ -35,6 +35,8 @@ defmodule Pleroma.Upload.Filter.Exiftool.ReadDescription do
       {tag_content, 0} =
         System.cmd("exiftool", ["-b", "-s3", tag, file], stderr_to_stdout: true, parallelism: true)
 
+      tag_content = String.trim(tag_content)
+
       if tag_content != "" and
            String.length(tag_content) <=
              Pleroma.Config.get([:instance, :description_limit]),