fix: update workoutSubTypeId handling in TPWorkoutLibraryItemDTO and CreateTPWorkoutRequestDTO

Author: costa-alex

boot/src/main/kotlin/org/freekode/tp2intervals/infrastructure/platform/trainingpeaks/library/TPWorkoutLibraryItemDTO.kt

@@ -6,6 +6,7 @@ import org.freekode.tp2intervals.infrastructure.platform.trainingpeaks.workout.s
 class TPWorkoutLibraryItemDTO(
     exerciseLibraryItemId: String,
     workoutTypeId: Int,
+    workoutSubTypeId: Int,
     itemName: String,
     totalTimePlanned: Double?,
     tssPlanned: Int?,
@@ -15,6 +16,7 @@ class TPWorkoutLibraryItemDTO(
 ) : TPBaseWorkoutResponseDTO(
     exerciseLibraryItemId,
     workoutTypeId,
+    workoutSubTypeId,
     itemName,
     totalTimePlanned,
     tssPlanned,

boot/src/main/kotlin/org/freekode/tp2intervals/infrastructure/platform/trainingpeaks/workout/CreateTPWorkoutRequestDTO.kt

@@ -8,7 +8,7 @@ class CreateTPWorkoutRequestDTO(
     var athleteId: String,
     var workoutDay: LocalDate,
     var workoutTypeValueId: Int,
-    var workoutSubTypeValueId: Int? = null,
+    var workoutSubTypeValueId: Int?,
     var title: String,
     var description: String?,
     var totalTime: Double?,