Bump postcss from 8.4.27 to 8.4.28 (#973)

Author: dependabot[bot]

package.json

@@ -22,7 +22,7 @@
     "cross-env": "7.0.3",
     "css-loader": "6.8.1",
     "mini-css-extract-plugin": "2.7.6",
-    "postcss": "8.4.27",
+    "postcss": "8.4.28",
     "postcss-loader": "7.3.3",
     "postcss-scss": "4.0.6",
     "sass": "1.65.1",