Bump less from 3.10.3 to 4.1.2 in /packages/playground

Bumps [less](https://github.com/less/less.js) from 3.10.3 to 4.1.2.
- [Release notes](https://github.com/less/less.js/releases)
- [Changelog](https://github.com/less/less.js/blob/master/CHANGELOG.md)
- [Commits](https://github.com/less/less.js/compare/v3.10.3...v4.1.2)

---
updated-dependencies:
- dependency-name: less
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

packages/playground/package.json

@@ -22,7 +22,7 @@
     "gh-pages": "3.2.3",
     "jstat": "1.9.5",
     "lenses-ppx": "6.1.10",
-    "less": "3.10.3",
+    "less": "4.1.2",
     "lodash": "4.17.21",
     "mathjs": "10.4.1",
     "moduleserve": "0.9.1",