fix: Capitalize 'T' in "Dark Theme"

[Youssef1313]

GitHub Issue (If applicable): closes https://github.com/unoplatform/uno/issues/17755

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• [ ] Tested code with current supported SDKs
• [ ] Docs have been added/updated which fit documentation template. (for bug fixes / features)
• [ ] Unit Tests and/or UI Tests for the changes have been added (for bug fixes / features) (if applicable)
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• [ ] Contains NO breaking changes
• [ ] Updated the Release Notes
• [ ] Associated with an issue (GitHub or internal)

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