Fix thunderbird ack time

app/src/main/java/org/tasks/caldav/iCalendar.kt

@@ -47,6 +47,7 @@ import org.tasks.data.TagData
 import org.tasks.data.TagDataDao
 import org.tasks.date.DateTimeUtils.newDateTime
 import org.tasks.date.DateTimeUtils.toDateTime
+import org.tasks.date.DateTimeUtils.toLocal
 import org.tasks.jobs.WorkManager
 import org.tasks.location.GeofenceApi
 import org.tasks.notifications.NotificationManager
@@ -381,7 +382,7 @@ class iCalendar @Inject constructor(
                                     ?: unknownProperties.add(
                                             XProperty(MOZ_SNOOZE_TIME, utc.toString())
                                     )
-                            lastAck = lastModified
+                            lastAck = lastModified?.toLocal()
                         }
                         ?: unknownProperties.removeIf(IS_MOZ_SNOOZE_TIME)
             }

app/src/main/java/org/tasks/date/DateTimeUtils.kt

@@ -1,6 +1,7 @@
 package org.tasks.date
 
 import org.tasks.time.DateTime
+import org.tasks.time.DateTime.UTC
 import java.util.*
 
 object DateTimeUtils {
@@ -29,4 +30,6 @@ object DateTimeUtils {
     fun Long.toDateTime(): DateTime = DateTime(this)
 
     fun Long.isAfterNow(): Boolean = DateTime(this).isAfterNow
+
+    fun Long.toLocal(): Long = DateTime(this, UTC).toLocal().millis
 }