fix: ensure dirs are presented with trailing slash

Prevent invalid links always starting from
the webserver root.

src/main.rs

@@ -172,7 +172,7 @@ async fn file_view(
     let folders = s3_objects.common_prefixes.into_iter().map(|dir| {
         let dirname = dir.parts().last().unwrap();
         FileViewItem {
-            path: dirname.as_ref().into(),
+            path: format!("{}/", dirname.as_ref().to_string()),
             size_bytes: 0,
             size: "[DIR]".to_owned(),
             last_modification: String::default(),