Bump postcss from 8.4.28 to 8.4.31 in /packages/quick_start_browser (#274)

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

packages/quick_start_browser/package-lock.json

@@ -5045,9 +5045,9 @@
       }
     },
     "node_modules/postcss": {
-      "version": "8.4.28",
-      "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.4.28.tgz",
-      "integrity": "sha512-Z7V5j0cq8oEKyejIKfpD8b4eBy9cwW2JWPk0+fB1HOAMsfHbnAXLLS+PfVWlzMSLQaWttKDt607I0XHmpE67Vw==",
+      "version": "8.4.31",
+      "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.4.31.tgz",
+      "integrity": "sha512-PS08Iboia9mts/2ygV3eLpY5ghnUcfLV/EXTOW1E2qYxJKGGBUtNjN76FYHnMs36RmARn41bC0AZmn+rR0OVpQ==",
       "dev": true,
       "funding": [
         {