chore: use `prepublishOnly` instead of `prepublish` and run `npm install` in `prepublishOnly` script

[yoshinorin]

What does it do?

prepublish has been deprecated.

Screenshots

N/A

Pull request tasks

• [ ] Add test cases for the changes.
• [ ] Passed the CI test.

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Thanks :)

[github-actions[bot]]

How to test

git clone -b chore/use-prepublishOnly https://github.com/hexojs/hexo.git
cd hexo
npm install
npm test

[coveralls]

Pull Request Test Coverage Report for Build 7585012378

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 99.525%

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Totals
Change from base Build 7584840837:	0.0%
Covered Lines:	9218
Relevant Lines:	9262

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💛 - Coveralls