Bump postcss from 8.4.20 to 8.4.21 (#3041)

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.20 to 8.4.21.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](https://github.com/postcss/postcss/compare/8.4.20...8.4.21)

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

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

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

package.json

@@ -109,7 +109,7 @@
     "lefthook": "^1.2.6",
     "mini-css-extract-plugin": "^2.7.2",
     "npm-run-all": "^4.1.5",
-    "postcss": "^8.4.20",
+    "postcss": "^8.4.21",
     "postcss-scss": "^4.0.6",
     "prettier": "^2.8.2",
     "rimraf": "^3.0.2",

yarn.lock

@@ -7006,10 +7006,10 @@ postcss@^7.0.36:
     picocolors "^0.2.1"
     source-map "^0.6.1"
 
-postcss@^8.3.11, postcss@^8.4.14, postcss@^8.4.17, postcss@^8.4.19, postcss@^8.4.20:
-  version "8.4.20"
-  resolved "https://registry.yarnpkg.com/postcss/-/postcss-8.4.20.tgz#64c52f509644cecad8567e949f4081d98349dc56"
-  integrity sha512-6Q04AXR1212bXr5fh03u8aAwbLxAQNGQ/Q1LNa0VfOI06ZAlhPHtQvE4OIdpj4kLThXilalPnmDSOD65DcHt+g==
+postcss@^8.3.11, postcss@^8.4.14, postcss@^8.4.17, postcss@^8.4.19, postcss@^8.4.21:
+  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==
   dependencies:
     nanoid "^3.3.4"
     picocolors "^1.0.0"