Unexpected behavior when using `@` operator for right matrix multiplication of `PaillierEncryptedNumber` and `numpy.ndarray`

[fangxiaoran]

Issue
When performing right matrix multiplication of a PaillierEncryptedNumber instance with a numpy.ndarray using @ operator, numpy.ndarray.__matmul__ is called instead of the expected PaillierEncryptedNumber.__rmatmul__.

Reproduction

1. Instantiate a numpy.ndarray and a PaillierEncryptedNumber.
2. Perform ndarray @ paillierencryptednumer_instance.

Expected
The PaillierEncryptedNumber.__rmatmul__ method should be called.

Environment

• Numpy version: 1.23.1