chore(deps): bump postcss from 8.4.24 to 8.4.31 in /frontend

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.24 to 8.4.31.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.4.24...8.4.31)

---
updated-dependencies:
- dependency-name: postcss
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

frontend/package.json

@@ -54,7 +54,7 @@
     "mathjs": "^11.8.2",
     "mini-css-extract-plugin": "^2.7.6",
     "moment": "^2.29.4",
-    "postcss": "^8.4.21",
+    "postcss": "^8.4.31",
     "postcss-flexbugs-fixes": "^5.0.2",
     "postcss-loader": "^7.3.3",
     "postcss-normalize": "^10.0.1",

frontend/yarn.lock

@@ -9273,10 +9273,10 @@ postcss-value-parser@^4.0.0, postcss-value-parser@^4.1.0, postcss-value-parser@^
   resolved "https://registry.npmjs.org/postcss-value-parser/-/postcss-value-parser-4.2.0.tgz"
   integrity sha512-1NNCs6uurfkVbeXG4S8JFT9t19m45ICnif8zWLd5oPSZ50QnwMfK+H3jv408d4jw/7Bttv5axS5IiHoLaVNHeQ==
 
-postcss@^8.2.14, postcss@^8.4.21, postcss@^8.4.23, postcss@^8.4.24:
-  version "8.4.24"
-  resolved "https://registry.yarnpkg.com/postcss/-/postcss-8.4.24.tgz#f714dba9b2284be3cc07dbd2fc57ee4dc972d2df"
-  integrity sha512-M0RzbcI0sO/XJNucsGjvWU9ERWxb/ytp1w6dKtxTKgixdtQDq4rmx/g8W1hnaheq9jgwL/oyEdH5Bc4WwJKMqg==
+postcss@^8.2.14, postcss@^8.4.21, postcss@^8.4.23, postcss@^8.4.24, postcss@^8.4.31:
+  version "8.4.31"
+  resolved "https://registry.yarnpkg.com/postcss/-/postcss-8.4.31.tgz#92b451050a9f914da6755af352bdc0192508656d"
+  integrity sha512-PS08Iboia9mts/2ygV3eLpY5ghnUcfLV/EXTOW1E2qYxJKGGBUtNjN76FYHnMs36RmARn41bC0AZmn+rR0OVpQ==
   dependencies:
     nanoid "^3.3.6"
     picocolors "^1.0.0"