delete contacts on a background thread

app/src/main/kotlin/com/simplemobiletools/contacts/helpers/ContactsHelper.kt

@@ -1044,6 +1044,7 @@ class ContactsHelper(val activity: BaseSimpleActivity) {
     }
 
     fun deleteContacts(contacts: ArrayList<Contact>) {
+        Thread {
             val localContacts = contacts.filter { it.source == SMT_PRIVATE }.map { it.id.toString() }.toTypedArray()
             activity.dbHelper.deleteContacts(localContacts)
 
@@ -1064,5 +1065,6 @@ class ContactsHelper(val activity: BaseSimpleActivity) {
             } catch (e: Exception) {
                 activity.showErrorToast(e)
             }
+        }.start()
     }
 }