Doesn't download media in best/original resolution#24

<!--- !! PLEASE READ !! Before submitting an issue: - Make sure you have read the README, as well as any applicable documentation. - Search older issues to see if your issue was already submitted. Provide the following information, if possible: - The version (commit hash) of tumblr-utils you are using. - If you do not know this, provide the approximate date at which you last downloaded/updated tumblr-utils. - The exact command you ran (excluding blog names if you prefer) - Any relevant console output from tumblr-utils. - For crashes, a backtrace (if available). - For post-specific issues: Either an example post (blog + ID, or url), or the relevant JSON from that post (use -j) --> I downloaded this fork of tumblr-utils yesterday (June 10, 2024) and comparing the media resolution with [Tumblthree's](https://github.com/TumblThreeApp/TumblThree) downloaded files, this one is much smaller. I downloaded a blog using the basic `tumblr-backup blog-name` command, and looking at the media files, an image was only 640x640 while on TumblThree it downloaded the image as 1024x1024. I haven't tried it out on gifs and videos yet, so I'm not sure what resolution they download as. Is there any way to always download the best possible resolution for the media?