Update `WikiMed Medical Encyclopedia` to support Android 15.

See issue https://github.com/kiwix/kiwix-android/issues/4270. As our Kiwix app now supports Android 15 so our custom app should also support Android 15.

**Folder Name:** [wikimed](https://github.com/kiwix/kiwix-android-custom/tree/main/wikimed)
**Package Name:** `org.kiwix.kiwixcustomwikimed`


![Image](https://github.com/user-attachments/assets/b586be26-e644-46ee-9c69-9ebf6462e786)