5.0.0

Change

• 4049b1f Update @types/unist
  migrate: update too
• 91eee7f Change to require Node.js 16
  migrate: update too
• fda0351 Change to use export map
  migrate: don’t use private APIs
• e396010 Change to return undefined for invalid points, positions
  by @wooorm in #12
  migrate: expect undefined

Full Changelog: 4.0.4...5.0.0