Fixed: Only one ZIM file was displayed when multiple ZIM files had the same title and language.

* The issue occurred because ZIM files in the local library were being filtered based on their title and language. As a result, if multiple ZIM files shared the same title and language (e.g., English), only one of them was shown on the Local Library screen.
* Since each ZIM file has a unique bookId, we now remove duplicates based on the bookId instead.

Author: MohitMaliDeveloper

core/src/main/java/org/kiwix/kiwixmobile/core/data/Repository.kt

@@ -74,7 +74,7 @@ class Repository @Inject internal constructor(
           } else {
             listOf(bookOnDisk)
           }
-        }.distinctBy { it.book.language to it.book.title }
+        }.distinctBy { it.book.id }
           .sortedBy { it.book.language + it.book.title }
       }
       .map { items ->