chore: fix lint error

[shuuji3]

🔗 Linked issue

N/A (see #345)

❓ Type of change

• 📖 Documentation (updates to the documentation, readme, or JSdoc annotations)
• 📰 Content (a new article or a change in the content folder)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

This PR fixes the lint error on the main branch. The previous GitHub Actions log was removed now, but it I found out there were only two simple lint errors.

The error of pnpm run lint fixed:

$ pnpm run lint

> website@ lint /home/shuuji3/dev/unjs-website
> eslint .

(node:1034756) [DEP0180] DeprecationWarning: fs.Stats constructor is deprecated.
(Use `node --trace-deprecation ...` to show where the warning was created)

/home/shuuji3/dev/unjs-website/components/app/AppAlert.vue
  10:23  error  Expected to return a value in computed function  vue/return-in-computed-property

/home/shuuji3/dev/unjs-website/components/learn/LearnCard.vue
  13:31  error  Expected to return a value in computed function  vue/return-in-computed-property

✖ 2 problems (2 errors, 0 warnings)

 ELIFECYCLE  Command failed with exit code 1.

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.
  • N/A - no need to modify documentation for this lint fix.