Joypad motion isn't serialized or restored

[Repflez]

Describe the bug
When calling InputHelper.serialize_inputs_for_actions(), joypad axis bindings aren't saved, neither can be restored.

Affected version

• Input Helper version: 4.2.2
• Godot version: 4.2.rc2

To Reproduce
Steps to reproduce the behavior:

1. Create an input map that uses a joypad axis
2. Serialize them with InputHelper.serialize_inputs_for_actions()
3. Apply the serialized inputs with InputHelper.deserialize_inputs_for_actions(serialized_inputs)
4. Try to use the previously created input map with a joypad axis

Expected behavior
The joypad axis should be saved and restored properly for the input maps that use them.

Screenshots
None