feat: add stats/incr/nanmse

[hrshya]

Resolves #5608 .

Description

What is the purpose of this pull request?

This pull request:

• adds stats/incr/nanmse .

Related Issues

Does this pull request have any related issues?

This pull request:

• resolves no related issues.

Questions

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No.

Other

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No.

Checklist

Please ensure the following tasks are completed before submitting this pull request.

• Read, understood, and followed the contributing guidelines.

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[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
stats/incr/nanmse	$\color{green}129/129$ $\color{green}+100.00\%$	$\color{green}8/8$ $\color{green}+100.00\%$	$\color{green}2/2$ $\color{green}+100.00\%$	$\color{green}129/129$ $\color{green}+100.00\%$

The above coverage report was generated for the changes in this PR.

[hrshya]

/stdlib lint-autofix