Update dependency postcss to v8.4.8

Author: renovate-bot

package.json

@@ -74,7 +74,7 @@
     "jest": "27.5.1",
     "lint-staged": "12.3.5",
     "lodash-es": "4.17.21",
-    "postcss": "8.4.7",
+    "postcss": "8.4.8",
     "prettier": "2.5.1",
     "react": "17.0.2",
     "react-dom": "17.0.2",