Non-default styles do not execute transitions properly

[aspencuozzo]

The problem

Describe the bug
When a background is called to transition through the built-in options (ie. Simple Fade) while Dialogic is using a style that is not the default style (ie. a character style), the transition does not start and the background is instead abruptly displayed on screen.

To Reproduce

1. Create a new Godot project and install Dialogic from main.
2. Create basic test enviroment (new timeline, new character, one default style and one character style).
3. Start a background transition in the timeline while Dialogic is using the default style. This should function as intended.
4. Give the character its own style that is not the default style, and have it speak in the timeline. The background should fail to transition properly.

Expected behavior
The transition should execute as intended.

System (please complete the following information):

• OS: Windows & macOS (reproducible on both)
• Godot Version: 4.2.1 stable
• Dialogic Version: Latest from main

Possible fixes
The following warning is shown in the debugger when a transition fails to execute properly:

W 0:00:01:0725   start: Target object freed before starting, aborting Tweener.
  <C++ Source>   scene/animation/tween.cpp:548 @ start()