fix(HMCLCore): do not init JavaFX in JTest.

Author: huanghongxun

HMCLCore/src/test/java/org/jackhuang/hmcl/util/TaskTest.java

@@ -80,7 +80,7 @@ public void testWithCompose() {
     public void testThenAccept() {
         AtomicBoolean flag = new AtomicBoolean();
         boolean result = Task.supplyAsync(JavaVersion::fromCurrentEnvironment)
-                .thenAcceptAsync(Schedulers.javafx(), javaVersion -> {
+                .thenAcceptAsync(Schedulers.io(), javaVersion -> {
                     flag.set(true);
                     assertEquals(javaVersion, JavaVersion.fromCurrentEnvironment());
                 })