Add missing dependency for types

[Methuselah96]

Initial checklist

• I read the support docs
• I read the contributing guide
• I agree to follow the code of conduct
• I searched issues and couldn’t find anything (or linked relevant results below)
• If applicable, I’ve added docs and tests

Description of changes

Fix these build errors:

ERROR in ../../.yarn/cache/unist-util-position-npm-4.0.1-b1dc7e42c7-0fad25db39.zip/node_modules/unist-util-position/index.d.ts 22:31-38
TS2307: Cannot find module 'unist' or its corresponding type declarations.
    20 |  */
    21 | export function pointEnd(node?: NodeLike): Point
  > 22 | export type Position = import('unist').Position
       |                               ^^^^^^^
    23 | export type Point = import('unist').Point
    24 | export type PointLike = Partial<Point>
    25 | export type PositionLike = {

ERROR in ../../.yarn/cache/unist-util-position-npm-4.0.1-b1dc7e42c7-0fad25db39.zip/node_modules/unist-util-position/index.d.ts 23:28-35
TS2307: Cannot find module 'unist' or its corresponding type declarations.
    21 | export function pointEnd(node?: NodeLike): Point
    22 | export type Position = import('unist').Position
  > 23 | export type Point = import('unist').Point
       |                            ^^^^^^^
    24 | export type PointLike = Partial<Point>
    25 | export type PositionLike = {
    26 |   start?: PointLike