Upgrade JavaFX Version

Upgrading to the newest LTS version. The previous version had issues on
some Apple Silicon machines.

Author: bkthomps

pom.xml

@@ -19,17 +19,17 @@
         <dependency>
             <groupId>org.openjfx</groupId>
             <artifactId>javafx-controls</artifactId>
-            <version>18.0.1</version>
+            <version>21.0.8</version>
         </dependency>
         <dependency>
             <groupId>org.openjfx</groupId>
             <artifactId>javafx-fxml</artifactId>
-            <version>18.0.1</version>
+            <version>21.0.8</version>
         </dependency>
         <dependency>
             <groupId>org.openjfx</groupId>
             <artifactId>javafx-media</artifactId>
-            <version>18.0.1</version>
+            <version>21.0.8</version>
         </dependency>
         <dependency>
             <groupId>org.junit.jupiter</groupId>