chore(deps): update dependency postcss to v8.4.12

Author: renovate-bot

package-lock.json

@@ -48,7 +48,7 @@
     "lodash": "4.17.21",
     "node-sass": "7.0.1",
     "npm-run-all": "4.1.5",
-    "postcss": "8.4.8",
+    "postcss": "8.4.12",
     "postcss-cli": "9.1.0",
     "postcss-load-config": "3.1.3",
     "rollup": "2.70.1",