Multiline class output fix

[funny-family]

🤔 What is the nature of this change?

• [ ] New feature
• [x] Fix bug
• [ ] Style optimization
• [ ] Code style optimization
• [ ] Performance optimization
• [ ] Build optimization
• [ ] Refactor code or style
• [ ] Test related
• [ ] Other

🔗 Related Issue

💡 Background or solution

📝 Changelog

Language	Changelog
🇺🇸 English	Fix multi line class output. Close issue: https://github.com/vuejs/babel-plugin-jsx/issues/569
🇨🇳 Chinese

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• [x] Doc is updated/provided or not needed (not needed)
• [x] Demo is updated/provided or not needed (not needed)
• [x] TypeScript definition is updated/provided or not needed (not needed)
• [x] Changelog is provided or not needed (need)

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[funny-family]

@Amour1688 cc

[sxzz]

Thanks for the PR. We can directly use transformJSXText function 8ed497de1dded45e51535bd55ac5b91e9718d5a9