refactor: use !!v insetead of Boolean(v) to reduce bundle size

[EdamAme-x]

The author should do the following, if applicable

• Add tests
• Run tests
• bun run format:fix && bun run lint:fix to format the code
• Add TSDoc/JSDoc to document the code

[EdamAme-x]

I don't know why to failed tests

The types of result seems to be Promise<string> | undefined...?
https://github.com/honojs/hono/blob/55cec8b522f4eac1636e03511c3683f7f04f9f47/src/utils/html.ts#L16

[yusukebe]

@EdamAme-x

If this is ready for review, please ping me!