Add support for pnpm/package.yaml

[sghuang19]

Check List

• I have already read README.
• I have already searched existing issues.
• I have already searched existing pull requrests.

Feature Request

Currently only a repo with a package.json present can be recognized as a valid Hexo blog repo. i.e. in an unrecognized directory, I need to run hexo init first. It would be great to take package.yaml, which is used by pnpm into consideration.

Additional context

hexo-cli/lib/hexo.ts

Line 75 in 267b149

entry.version = require('../package.json').version as string;

It might have something to do with this line.