chore(deps): bump hexo-front-matter from 4.0.0 to ^4.2.1

[uiolee]

The former one should be fixed in https://github.com/hexojs/hexo-front-matter/pull/67, but since hexo-front-matter hasn't released a new version to include this change yet, we should still stick to v4.0.0 here to prevent type error.

Originally posted by @Pcrab in https://github.com/hexojs/hexo/issues/5202#issuecomment-1544052137

What does it do?

bump hexo-front-matter from 4.0.0 to ^4.2.0

Require

dont merge this PR before:

• [x] publish hexo-front-matter@4.2.0 (hexojs/hexo-front-matter#129)
• [x] #5271

[github-actions[bot]]

How to test

git clone -b front-420 https://github.com/uiolee/hexo.git
cd hexo
npm install
npm test

[coveralls]

Pull Request Test Coverage Report for Build 6706873263

• 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 99.535%

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Totals
Change from base Build 6706758484:	0.0%
Covered Lines:	8997
Relevant Lines:	9039

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💛 - Coveralls