Numpy version of texar could be updated to 1.21 to support typing

[hepengfe]

Describe the bug

To fix #90, I use numpy.typing.ndarray as return typing, but it's only supported in nunpy==1.21.

https://github.com/asyml/forte-wrappers/runs/5368790872?check_suite_focus=true

To Reproduce
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1. Prepare data ...
2. Run command '....'
3. See error

Expected behavior
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• Version [e.g. 22]
• Python and Package verions: [e.g. Python version, Pytorch version]

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