feat: upgrade next-mdx-remote

* chore: upgrade packages

Updating packages:
- "@mapbox/rehype-prism": "^0.6.0"
- "image-size": "1.0.0"
- "next-seo": "4.24.0"
- "remark-code-titles": "0.1.2"
- "remark-footnotes": "^3.0.0"
- "eslint-config-prettier": "^8.3.0"
- "globby": "11.0.3"
- "lint-staged": "^11.0.0"
- "remark-stringify": "9.0.1"

* feat: upgrade next-mdx-remote

It adds MDXRemote and serialize breaking changes

Read more at https://github.com/hashicorp/next-mdx-remote/releases/tag/3.0.0

* fix: downgrade remark-math and rehype-katex

lib/mdx.js

@@ -1,7 +1,7 @@
 import MDXComponents from '@/components/MDXComponents'
 import fs from 'fs'
 import matter from 'gray-matter'
-import renderToString from 'next-mdx-remote/render-to-string'
+import { serialize } from 'next-mdx-remote/serialize'
 import path from 'path'
 import readingTime from 'reading-time'
 import visit from 'unist-util-visit'
@@ -49,7 +49,7 @@ export async function getFileBySlug(type, slug) {
     : fs.readFileSync(mdPath, 'utf8')
 
   const { data, content } = matter(source)
-  const mdxSource = await renderToString(content, {
+  const mdxSource = await serialize(content, {
     components: MDXComponents,
     mdxOptions: {
       remarkPlugins: [