remove unused background list_selector on grid_item

Signed-off-by: Abdourahamane BOINAIDI <abdourahamane.boinaidi@infomaniak.com>

src/main/res/layout/grid_item.xml

@@ -20,7 +20,6 @@
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
     android:layout_gravity="center_horizontal"
-    android:background="@drawable/list_selector"
     android:gravity="center"
     android:orientation="vertical">