docs: fix GitHub Actions spelling in reporter and documentation

[chenjiahan]

Summary

Fix GitHub Actions spelling in reporter and documentation (github actions -> GitHub Actions).

Checklist

• Tests updated (or not required).
• Documentation updated (or not required).

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[Copilot]

Pull Request Overview

This PR corrects the spelling of "GitHub Actions" across documentation and reporter code, changing inconsistent usage of "Github actions" and "github actions" to the proper capitalized form "GitHub Actions".

Key Changes:

• Standardized capitalization of "GitHub Actions" in English and Chinese documentation
• Updated log message in GitHub Actions reporter to use correct capitalization and improved grammar

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
website/docs/zh/config/test/reporters.mdx	Updated Chinese documentation to use proper "GitHub Actions" capitalization in heading and body text
website/docs/en/config/test/reporters.mdx	Updated English documentation to use proper "GitHub Actions" capitalization in heading and body text
packages/core/src/reporter/githubActions.ts	Corrected log message capitalization and grammar from "error for github actions" to "Error for GitHub Actions"

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