chore: bump postcss from 8.4.21 to 8.4.31 in /example

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.21 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@8.4.21...8.4.31)

---
updated-dependencies:
- dependency-name: postcss
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <[email protected]>

example/yarn.lock

@@ -7587,10 +7587,10 @@ mz@^2.7.0:
     object-assign "^4.0.1"
     thenify-all "^1.0.0"
 
-nanoid@^3.3.4:
-  version "3.3.4"
-  resolved "https://registry.yarnpkg.com/nanoid/-/nanoid-3.3.4.tgz#730b67e3cd09e2deacf03c027c81c9d9dbc5e8ab"
-  integrity sha512-MqBkQh/OHTS2egovRtLk45wEyNXwF+cokD+1YPf9u5VfJiRdAiRwB2froX5Co9Rh20xs4siNPm8naNotSD6RBw==
+nanoid@^3.3.6:
+  version "3.3.6"
+  resolved "https://registry.yarnpkg.com/nanoid/-/nanoid-3.3.6.tgz#443380c856d6e9f9824267d960b4236ad583ea4c"
+  integrity sha512-BGcqMMJuToF7i1rt+2PWSNVnWIkGCU78jBG3RxO/bZlnZPK2Cmi2QaffxGO/2RvWi9sL+FAiRiXMgsyxQ1DIDA==
 
 nanomatch@^1.2.9:
   version "1.2.13"
@@ -8525,11 +8525,11 @@ postcss-value-parser@^4.1.0, postcss-value-parser@^4.2.0:
   integrity sha512-1NNCs6uurfkVbeXG4S8JFT9t19m45ICnif8zWLd5oPSZ50QnwMfK+H3jv408d4jw/7Bttv5axS5IiHoLaVNHeQ==
 
 postcss@^8.3.5, postcss@^8.4.19:
-  version "8.4.21"
-  resolved "https://registry.yarnpkg.com/postcss/-/postcss-8.4.21.tgz#c639b719a57efc3187b13a1d765675485f4134f4"
-  integrity sha512-tP7u/Sn/dVxK2NnruI4H9BG+x+Wxz6oeZ1cJ8P6G/PZY0IKk4k/63TDsQf2kQq3+qoJeLm2kIBUNlZe3zgb4Zg==
+  version "8.4.31"
+  resolved "https://registry.yarnpkg.com/postcss/-/postcss-8.4.31.tgz#92b451050a9f914da6755af352bdc0192508656d"
+  integrity sha512-PS08Iboia9mts/2ygV3eLpY5ghnUcfLV/EXTOW1E2qYxJKGGBUtNjN76FYHnMs36RmARn41bC0AZmn+rR0OVpQ==
   dependencies:
-    nanoid "^3.3.4"
+    nanoid "^3.3.6"
     picocolors "^1.0.0"
     source-map-js "^1.0.2"