Describe the bug

Before v51.5.0, creating index.html allows set meta tags (for charset="utf-8",og:title or more), it's could not to do...
is it casused by #2096 ?

Minimal reproduction

Steps to reproduce the behavior:

1. Run npm create slidev@latest
2. Add a frontmatter seoMeta to set og:image like bellow
3. Launch dev server with npm run dev and open https://localhost:3030
4. Open devtools with check meta tag to broken encoding (like screenshot)

seoMeta:
 ogTitle: マルチバイト文字のテスト

Environment

• Slidev version: v51.5.0
• Browser: Chrome
• OS: macOS