Normalize volume (#53)

app/src/main/kotlin/it/vfsfitvnm/vimusic/Database.kt

@@ -129,12 +129,13 @@ interface Database {
     views = [
         SortedSongInPlaylist::class
     ],
-    version = 4,
+    version = 5,
     exportSchema = true,
     autoMigrations = [
         AutoMigration(from = 1, to = 2),
         AutoMigration(from = 2, to = 3),
         AutoMigration(from = 3, to = 4, spec = DatabaseInitializer.From3To4Migration::class),
+        AutoMigration(from = 4, to = 5),
     ],
 )
 abstract class DatabaseInitializer protected constructor() : RoomDatabase() {