Fix duration check for uploads from twitter

Some twitter videos near the max duration had some stray
milliseconds that made the check fail.

For example
https://twitter.com/kivo_some_18/status/1152167154059321344?s=20 (nsfw)
has 140.053333 duration.

app/models/upload.rb

@@ -55,7 +55,7 @@ class Upload < ApplicationRecord
     end
 
     def validate_video_duration(record)
-      if !record.uploader.is_admin? && record.file.is_video? && record.file.duration > MAX_VIDEO_DURATION
+      if !record.uploader.is_admin? && record.file.is_video? && record.file.duration.to_i > MAX_VIDEO_DURATION
         record.errors.add(:base, "video must not be longer than #{MAX_VIDEO_DURATION.seconds.inspect}")
       end
     end