chore: update repository key from a string to an object in package.json

[yoshinorin]

Why?

As is the title.

See: https://docs.npmjs.com/cli/v10/configuring-npm/package-json#repository

Log

Warning log when I run npm publish --dry-run.

$ npm publish --dry-run
npm WARN publish npm auto-corrected some errors in your package.json when publishing.  Please run "npm pkg fix" to address these errors.
npm WARN publish errors corrected:
npm WARN publish "repository" was changed from a string to an object
npm WARN publish "repository.url" was normalized to "git+https://github.com/hexojs/hexo-deployer-ftpsync.git"
npm notice

---

Thanks :)

[coveralls]

coverage: 100.0%. remained the same
when pulling 90b7b23 on yoshinorin:chore/npm-pkg-fix
into b6ac346 on hexojs:master.