Tweak manga last updated time based on chapter upload instead of fetch time

app/src/main/java/eu/kanade/tachiyomi/util/ChapterSourceSync.kt

@@ -128,9 +128,9 @@ fun syncChaptersWithSource(db: DatabaseHelper,
         // Fix order in source.
         db.fixChaptersSourceOrder(sourceChapters).executeAsBlocking()
 
-        // Set manga's last update time to latest chapter's fetch time if possible
-        val newestChapter = db.getChapters(manga).executeAsBlocking().maxBy { it.date_fetch }
-        manga.last_update = newestChapter?.date_fetch ?: manga.last_update
+        // Set manga's last update time to latest chapter's upload time if possible
+        val newestChapter = db.getChapters(manga).executeAsBlocking().maxBy { it.date_upload }
+        manga.last_update = newestChapter?.date_upload ?: manga.last_update
         db.updateLastUpdated(manga).executeAsBlocking()
     }