Update dependency postcss to v8.5.23 [SECURITY]

Author: renovate[bot]

package.json

@@ -52,7 +52,7 @@
         "@rollup/plugin-terser": "1.0.0",
         "bestzip": "3.0.1",
         "gscan": "6.4.2",
-        "postcss": "8.5.15",
+        "postcss": "8.5.23",
         "postcss-import": "16.1.1",
         "postcss-preset-env": "11.3.0",
         "rollup": "4.62.3",