test(readarr): give each history fixture row a distinct quality

Two of the three rows carried the quality EPUB, so sorting by quality left them tied and any reordering confined to that pair was invisible. The rows now use EPUB, AZW3 and MOBI, matching the vocabulary the history UI fixture already uses.

This one is defensive: no natural mutation of the quality comparator flipped from surviving to failing, because two distinct values already separated the cross-field cases. The tie is removed on principle rather than to close a demonstrated hole.

src/handlers/readarr_handlers/history/history_handler_tests.rs

@@ -417,7 +417,7 @@ mod tests {
         event_type: ReadarrHistoryEventType::BookFileDeleted,
         quality: QualityWrapper {
           quality: Quality {
-            name: "EPUB".to_owned(),
+            name: "MOBI".to_owned(),
           },
         },
         date: DateTime::from(DateTime::parse_from_rfc3339("2024-03-10T07:28:45Z").unwrap()),