Bump @webref/css from 6.20.0 to 6.20.1 (#2139)

Author: dependabot[bot]

package-lock.json

@@ -96,7 +96,7 @@
     "@types/webidl2": "^24.4.3",
     "@types/yargs": "^17.0.33",
     "@typescript-eslint/eslint-plugin": "8.24.0",
-    "@webref/css": "6.20.0",
+    "@webref/css": "6.20.1",
     "@webref/elements": "^2.4.0",
     "@webref/idl": "3.59.4",
     "c8": "10.1.3",