Fix typos in the theme prop type

[connor-baer]

Purpose

While working on the dashboard, I noticed peculiar prop-type warnings from the themePropType. Turns out they were typos 🙈

Approach and changes

• Fixed the typos: theme.breakpoint → theme.breakpoints and theme.mx → theme.mq
• Added types to the prop-types so TypeScript will warn about typos in the future

Definition of done

• Development completed
• Reviewers assigned
• Unit and integration tests
• Meets minimum browser support
• Meets accessibility requirements

[changeset-bot]

🦋 Changeset detected

Latest commit: 0045e2e

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@sumup/design-tokens	Patch

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[vercel]

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[codecov]

Codecov Report

Merging #933 (0045e2e) into main (4660f11) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #933   +/-   ##
=======================================
  Coverage   91.87%   91.87%           
=======================================
  Files         161      161           
  Lines        2916     2916           
  Branches      727      727           
=======================================
  Hits         2679     2679           
  Misses        209      209           
  Partials       28       28           

Impacted Files	Coverage Δ
packages/design-tokens/utils/theme-prop-type.ts	0.00% <ø> (ø)