Setup Platform for runLater in GardenSchedule

Otherwise Test planTaskForCrop crashes due to unitialized Platform

src/test/java/ch/zhaw/gartenverwaltung/models/GardenScheduleTest.java

@@ -3,6 +3,9 @@ package ch.zhaw.gartenverwaltung.models;
 import ch.zhaw.gartenverwaltung.io.*;
 import ch.zhaw.gartenverwaltung.models.GardenSchedule;
 import ch.zhaw.gartenverwaltung.types.*;
+import javafx.application.Platform;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
@@ -29,6 +32,16 @@ class GardenScheduleTest {
     List<TaskTemplate> exampleTaskTemplateList;
     GardenSchedule model;
 
+    @BeforeAll
+    static void setUpAll() {
+        Platform.startup(()->{});
+    }
+
+    @AfterAll
+    static void tearDownAll() {
+        Platform.exit();
+    }
+
     @BeforeEach
     void setUp() throws IOException, HardinessZoneNotSetException {
         createExampleTaskList();