fix: deduplicate plugins

[danielroe]

🔗 Linked issue

❓ Type of change

• 📖 Documentation (updates to the documentation, readme, or JSdoc annotations)
• 🐞 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

Noticed when trying out https://github.com/pi0/nitro-cloudflare-dev/blob/main/src/index.ts that multiple copies of the same plugin were injected; this caused the following error:

[nitro 14:30:29]  ERROR  RollupError: virtual:#internal/nitro/virtual/plugins (6:7): Identifier "_BsBwid0Z5r" has already been declared


4: import _3SMM7tZjad from '/Users/daniel/code/danielroe/carpenter/node_modules/.pnpm/@nuxthub+core@0.5.11_ioredis@5.4.1...
5: import _BsBwid0Z5r from '/Users/daniel/code/danielroe/carpenter/node_modules/.pnpm/nitro-cloudflare-dev@0.1.4/node_mo...
6: import _BsBwid0Z5r from '/Users/daniel/code/danielroe/carpenter/node_modules/.pnpm/nitro-cloudflare-dev@0.1.4/node_mo...
          ^
7: 
8: export const plugins = [

The issue was user error - I was also using @nuxthub/core - but regardless, it seems like we should perhaps deduplicate?

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.