chore(deps): update dependency postcss to v8.5.5

Author: renovate[bot]

package-lock.json

@@ -34,7 +34,7 @@
     "gulp-uglify": "3.0.2",
     "gulp-zip": "5.1.0",
     "inquirer": "8.2.6",
-    "postcss": "8.4.39",
+    "postcss": "8.5.5",
     "postcss-color-mod-function": "3.0.3",
     "postcss-easy-import": "4.0.0",
     "pump": "3.0.0"