Bump postcss from 8.5.16 to 8.5.19 (#2385)

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

package-lock.json

@@ -42,7 +42,7 @@
     "markdown-it": "14.3.0",
     "markdown-it-container": "4.0.0",
     "npm-run-all": "4.1.5",
-    "postcss": "8.5.16",
+    "postcss": "8.5.19",
     "postcss-scss": "4.0.9",
     "postcss-url": "10.1.4",
     "posthtml": "0.16.7",