Unrestrict Filetypes on Drag-and-Drop file uploads

[viscountexx]

Description of the issue

WebP images are labeled as an "invalid file type" when you drag and drop them into the UI. However, if you use the usual file upload dialogue, they do work and are uploadable in Mastodon 4.1.4.

How you found the issue

Steps to reproduce the behavior:

1. Drag & drop a WebP image over the post box.
2. Observe that it says "invalid filetype"
3. Click the image upload button
4. Upload the same image successfully.

What you expected to happen

Both drag and drop and file upload should be consistent with eachother.

I think this check should probably not even be being made clientside, since supported filetypes for upload will vary per instance as time goes on and Mastodon and other software that supports the Mastodon API changes.

[viscountexx]

Update: I'm actually running into this filetype issue with plain PNGs as well. I think this is something related to a system bug I'm having that's causing my drag and drop state to get "stuck", but I still will leave the issue open with a rename, as I think it's best to not restrict the filetypes a user can try to upload on the clientside in a drag and drop step. If I'm connected to a server that lets me upload EXE files, Semaphore should be letting me do that, silly though it sounds.