MDX v2

[LekoArts]

Use MDX v2 and gatsby-plugin-mdx v4 with theme-ui v0.15 (For system-ui/theme-ui#2288 support)

TODOs:

• Cara
• Emilia
• Emma
• GraphQL Playground
• Jodie
• Minimal Blog
• Specimens
• Styleguide
• Code Titles working

[changeset-bot]

⚠️ No Changeset found

Latest commit: 5b21125

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