feat: add stats/nanmean

[gururaj1512]

Resolves None

Description

What is the purpose of this pull request?

This pull request:

• feat: add stats/nanmean

Related Issues

Does this pull request have any related issues?

This pull request:

• resolves None

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-js/reviewers

[kgryte]

/stdlib merge

[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
stats/nanmean	$\color{green}164/164$ $\color{green}+100.00\%$	$\color{green}2/2$ $\color{green}+100.00\%$	$\color{green}0/0$ $\color{green}+100.00\%$	$\color{green}164/164$ $\color{green}+100.00\%$

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

[kgryte]

LGTM after clean-up.