Update humanoid_seq_pose_controller.py

[xavierpuigf]

Make default offset a Vector3

Motivation and Context

Make default offset be a vector3 for humanoid

How Has This Been Tested

Ran tests:

Types of changes

• [Bug Fix] (non-breaking change which fixes an issue)

Checklist

• [ x] My code follows the code style of this project.
• [ x] I have updated the documentation if required.
• [ x] I have read the CONTRIBUTING document.
• [ x] I have completed my CLA (see CONTRIBUTING)
• [ x] I have added tests to cover my changes if required.