message: fix(core): export MigratableStateDescriptor
diff: @@ -147,7 +147,7 @@ interface AbstractMigratableStateDescriptor<InitialS, AllS, S, T, R>
  recursiveMigrate: (previousState: InitialS | Versionized<AllS>) => S
  }
  -interface MigratableStateDescriptor<InitialS, AllS, S, T, R>
  +export interface MigratableStateDescriptor<InitialS, AllS, S, T, R>
  extends AbstractMigratableStateDescriptor<InitialS, AllS, S, T, R> {
  migrate<S1, T1, R1>(
  nextType: StateDescriptor<S1, T1, R1>,
  