Dropping a file from a WebDAV folder onto GitHub comment transfers text address, not image

### What Happened?

Dragged a `.png` image from a WebDav location and dropped onto a GitHub comment
The image was not transferred - its address was. Equivalent operations with a local file worked correctly. Nautilus also worked with a WebDAV file.

### Steps to Reproduce

Open a WebDAV server location containing a `.png` file
Start to edit a GitHub comment
Drag and drop the `.png` file onto the comment
The address is transferred, not the image

### Expected Behavior

The behaviour of Nautilus should be matched.

### OS Version

8.x (Circe)

### OS Architecture

amd64 (on most hardwares)

### Session Type

Classic Session (X11, This is the default)

### Software Version

Latest release (I have run all updates)

### Log Output

```shell

```

### Hardware Info

_No response_