feat: add constants/float16/half-pi

[DivyanshuVortex]

---

type: pre_commit_static_analysis_report
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• task: lint_license_headers status: passed ---

Resolves #{{TODO: add issue number}}.

Description

What is the purpose of this pull request?

This pull request:

• add `constants/float16/half-pi

Related Issues

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This pull request has the following related issues:

• #{{TODO: add related issue number}}

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No.

Other

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• Read, understood, and followed the contributing guidelines.

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{{TODO: add disclosure if applicable}}

---

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[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
constants/float16/half-pi	$\color{green}45/45$ $\color{green}+0.00%$	$\color{green}1/1$ $\color{green}+0.00%$	$\color{green}0/0$ $\color{green}+0.00%$	$\color{green}45/45$ $\color{green}+0.00%$

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

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[kgryte]

@DivyanshuVortex Similar to #8918, you need to remove the C files from this PR.

[kgryte]

LGTM