Add foreign key constraint to Song

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

@@ -150,7 +150,7 @@ interface Database {
     views = [
         SortedSongInPlaylist::class
     ],
-    version = 9,
+    version = 10,
     exportSchema = true,
     autoMigrations = [
         AutoMigration(from = 1, to = 2),
@@ -160,6 +160,7 @@ interface Database {
         AutoMigration(from = 5, to = 6),
         AutoMigration(from = 6, to = 7),
         AutoMigration(from = 7, to = 8, spec = DatabaseInitializer.From7To8Migration::class),
+        AutoMigration(from = 9, to = 10),
     ],
 )
 @TypeConverters(Converters::class)

app/src/main/kotlin/it/vfsfitvnm/vimusic/models/Song.kt

@@ -4,14 +4,14 @@ import androidx.room.*
 
 
 @Entity(
-//    foreignKeys = [
-//        ForeignKey(
-//            entity = Album::class,
-//            parentColumns = ["id"],
-//            childColumns = ["albumId"],
-//            onDelete = ForeignKey.CASCADE
-//        ),
-//    ]
+    foreignKeys = [
+        ForeignKey(
+            entity = Album::class,
+            parentColumns = ["id"],
+            childColumns = ["albumId"],
+            onDelete = ForeignKey.SET_NULL
+        ),
+    ]
 )
 data class Song(
     @PrimaryKey val id: String,