Update devDependency vuepress to v1.9.8

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
vuepress	1.9.7 -> 1.9.8

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Release Notes

vuejs/vuepress

### [`v1.9.8`](https://togithub.com/vuejs/vuepress/blob/HEAD/CHANGELOG.md#​198-httpsgithubcomvuejsvuepresscomparev197v198-2023-01-06) [Compare Source](https://togithub.com/vuejs/vuepress/compare/v1.9.7...v1.9.8) ##### Bug Fixes - **cli:** `.vuepress/config.ts` does not respect custom command (close: [#​3113](https://togithub.com/vuejs/vuepress/issues/3113)) ([#​3114](https://togithub.com/vuejs/vuepress/issues/3114)) ([7cd8b30](https://togithub.com/vuejs/vuepress/commit/7cd8b3052d12db637ca4c8d839364d6e3f4932f7)) [@​ULIVZ](https://togithub.com/ULIVZ)

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Configuration

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