fix: use min-width in custom-media breakpoint definitions

[adamstankiewicz]

Description

Use min-width in custom css/custom-media-breakpoints style-dictionary format.

Deploy Preview

N/A

Merge Checklist

• If your update includes visual changes, have they been reviewed by a designer? Send them a link to the Netlify deploy preview, if applicable.
• Does your change adhere to the documented style conventions?
• Do any prop types have missing descriptions in the Props API tables in the documentation site (check deploy preview)?
• Were your changes tested using all available themes (see theme switcher in the header of the deploy preview, under the "Settings" icon)?
• Were your changes tested in the example app?
• Is there adequate test coverage for your changes?
• Consider whether this change needs to reviewed/QA'ed for accessibility (a11y). If so, please add wittjeff and adamstankiewicz as reviewers on this PR.

Post-merge Checklist

• Verify your changes were released to NPM at the expected version.
• If you'd like, share your contribution in #show-and-tell.
• 🎉 🙌 Celebrate! Thanks for your contribution.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.77%. Comparing base (a42ea75) to head (876bdc2).
Report is 1081 commits behind head on alpha.

Additional details and impacted files

@@           Coverage Diff           @@
##            alpha    #2098   +/-   ##
=======================================
  Coverage   90.77%   90.77%           
=======================================
  Files         213      213           
  Lines        3501     3501           
  Branches      843      843           
=======================================
  Hits         3178     3178           
  Misses        315      315           
  Partials        8        8           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[edx-semantic-release]

🎉 This PR is included in version 21.0.0-alpha.15 🎉

The release is available on:

• npm package (@alpha dist-tag)
• GitHub release

Your semantic-release bot 📦🚀

[edx-semantic-release]

🎉 This PR is included in version 22.0.0-alpha.1 🎉

The release is available on:

• npm package (@alpha dist-tag)
• GitHub release

Your semantic-release bot 📦🚀

[openedx-semantic-release-bot]

🎉 This PR is included in version 23.0.0-alpha.1 🎉

The release is available on:

• npm package (@alpha dist-tag)
• GitHub release

Your semantic-release bot 📦🚀

[openedx-semantic-release-bot]

🎉 This PR is included in version 23.0.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀