fix: upgrade playground-elements from 0.20.0 to 0.21.0

Snyk has created this PR to upgrade playground-elements from 0.20.0 to 0.21.0.

See this package in npm:
playground-elements

See this project in Snyk:
https://app.snyk.io/org/maicol07/project/7bc120c4-da8d-47a8-b76c-4553af1c8acb?utm_source=github&utm_medium=referral&page=upgrade-pr

Author: snyk-bot

catalog/package.json

@@ -173,7 +173,7 @@
     "@material/mwc-drawer": "^0.27.0",
     "@preact/signals-core": "^1.8.0",
     "lit": "^3.3.0",
-    "playground-elements": "^0.20.0",
+    "playground-elements": "^0.21.0",
     "postdoc-lib": "^1.0.3"
   },
   "devDependencies": {