Fix non-uniform contributor avatar sizes in README

[Copilot]

Contributor avatars rendered at inconsistent sizes because <img> tags only specified width with no height constraint.

• Added height="100" to each avatar <img> tag to enforce uniform 100×100px rendering
• Appended &s=100 to GitHub avatar URLs to request correctly sized images from the CDN

<!-- Before -->
<img src="https://avatars.githubusercontent.com/user?v=4" width="100" alt="user"/>

<!-- After -->
<img src="https://avatars.githubusercontent.com/user?v=4&s=100" width="100" height="100" alt="user"/>

Original prompt

contributor中头像大小不统一，请你设置一下

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[Copilot]

Pull request overview

Updates the README Contributors section to ensure GitHub avatar images render at a consistent size in the Markdown table.

Changes:

• Added height="100" to each contributor avatar <img> tag.
• Appended &s=100 to each GitHub avatar URL to request a correctly sized image.

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