Bump postcss from 8.4.23 to 8.4.31 in /extensions/web-widget

Dependabot couldn't find the original pull request head commit, b4ce5c5d7b37c529245006df293f65d8065dd513.

extensions/web-widget/package-lock.json

@@ -620,9 +620,9 @@
       }
     },
     "node_modules/postcss": {
-      "version": "8.4.23",
-      "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.4.23.tgz",
-      "integrity": "sha512-bQ3qMcpF6A/YjR55xtoTr0jGOlnPOKAIMdOWiv0EIT6HVPEaJiJB4NLljSbiHoC2RX7DN5Uvjtpbg1NPdwv1oA==",
+      "version": "8.4.31",
+      "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.4.31.tgz",
+      "integrity": "sha512-PS08Iboia9mts/2ygV3eLpY5ghnUcfLV/EXTOW1E2qYxJKGGBUtNjN76FYHnMs36RmARn41bC0AZmn+rR0OVpQ==",
       "dev": true,
       "funding": [
         {