Static Slerp method for quaternion is not normalized

[yangfengzzz]

Describe the bug
the output of Slerp is not normalized, the output quaternion can't turn to be the transformation matrix.

The unit tests use non-normalized test data, so it is not found before.

To Reproduce
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Expected behavior
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Desktop (please complete the following information):

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Smartphone (please complete the following information):

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