fix(AttachmentPreview): ext should not be case sensitive (#9426)

fix(AttachmentPreview): 修复图片扩展名大小写敏感问题

src/renderer/src/pages/home/Inputbar/AttachmentPreview.tsx

@@ -83,7 +83,7 @@ export const getFileIcon = (type?: string) => {
 export const FileNameRender: FC<{ file: FileMetadata }> = ({ file }) => {
   const [visible, setVisible] = useState<boolean>(false)
   const isImage = (ext: string) => {
-    return ['.png', '.jpg', '.jpeg', '.gif', '.bmp', '.webp'].includes(ext)
+    return ['.png', '.jpg', '.jpeg', '.gif', '.bmp', '.webp'].includes(ext.toLocaleLowerCase())
   }
 
   const fullName = FileManager.formatFileName(file)