Fix threading issue with scheduled message

app/src/main/kotlin/com/simplemobiletools/smsmessenger/activities/ThreadActivity.kt

@@ -1013,7 +1013,8 @@ class ThreadActivity : SimpleActivity() {
                     conversationsDB.insertOrUpdate(conversation.copy(date = nowSeconds))
                 }
                 scheduleMessage(message)
-            }
+
+                runOnUiThread {
                     clearCurrentMessage()
                     hideScheduleSendUi()
                     scheduledMessage = null
@@ -1021,6 +1022,8 @@ class ThreadActivity : SimpleActivity() {
                     if (!refreshedSinceSent) {
                         refreshMessages()
                     }
+                }
+            }
         } catch (e: Exception) {
             showErrorToast(e.localizedMessage ?: getString(R.string.unknown_error_occurred))
         }