chore(deps): bump Astro dependencies

- `@astrojs/markdown-remark`: 4.3.0 → 4.3.1
- `@astrojs/mdx`: 2.2.0 → 2.2.1
- `@astrojs/vercel`: 7.3.6 → 7.4.0
- `astro`: 4.5.6 → 4.5.8

Author: julien-deramond