chore: Use Bun instead of yarn as a package manager

[nakasyou]

I replaced yarn with Bun, just like Hono did.

Pros

• Yarn creates node_modules in all packages, so we need a lot of disc space.
  • Bun creates node_modules each packages, but common dependencies are ignored, so we can save disc spaces.
• To install is faster than yarn.

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Latest commit: 23f41a6

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