Set default value of the timezone state to null

Signed-off-by: Arnau Mora Gras <arnyminerz@proton.me>

app/src/main/kotlin/at/bitfire/davdroid/ui/account/CreateCalendarModel.kt

@@ -17,18 +17,17 @@ import dagger.assisted.Assisted
 import dagger.assisted.AssistedFactory
 import dagger.assisted.AssistedInject
 import dagger.hilt.android.lifecycle.HiltViewModel
+import java.text.Collator
+import java.time.ZoneId
+import java.time.format.TextStyle
+import java.util.Locale
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.SupervisorJob
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.flow
 import kotlinx.coroutines.flow.flowOn
 import kotlinx.coroutines.launch
-import java.text.Collator
-import java.time.ZoneId
-import java.time.format.TextStyle
-import java.util.Locale
-import java.util.TimeZone
 
 @HiltViewModel(assistedFactory = CreateCalendarModel.Factory::class)
 class CreateCalendarModel @AssistedInject constructor(
@@ -75,7 +74,7 @@ class CreateCalendarModel @AssistedInject constructor(
  val color: Int = Css3Color.entries.random().argb,
  val displayName: String = "",
  val description: String = "",
- val timeZoneId: String? = TimeZone.getDefault().id,
+ val timeZoneId: String? = null,
  val supportVEVENT: Boolean = true,
  val supportVTODO: Boolean = true,
  val supportVJOURNAL: Boolean = true,