fix: correct motion callback signature in JNI

Author: Eatgrapes

native/src/CubismUserModel_JNI.cpp

@@ -30,8 +30,8 @@ class JniUserModel : public CubismUserModel {
         auto* motion = CubismMotion::Create(buffer, size);
         if (!motion) return;
 
-        motion->SetFinishedMotionHandlerAndMotionCustomData([](ACubismMotion* self, void* data) {
-            auto* model = static_cast<JniUserModel*>(data);
+        motion->SetFinishedMotionHandlerAndMotionCustomData([](ACubismMotion* self) {
+            auto* model = static_cast<JniUserModel*>(self->GetFinishedMotionCustomData());
             model->notifyFinished();
             CubismMotion::Delete(static_cast<CubismMotion*>(self));
         }, this);
@@ -185,4 +185,4 @@ JNIEXPORT void JNICALL Java_dev_eatgrapes_live2d_CubismUserModel_drawNative(JNIE
     }
 }
 
-}
+}