Fix new npm vulnerability (postcss).

This is the same one that the dependabot made a pull request to main
for except updates to the latest version of `postcss`.

Author: drgrice1

htdocs/package-lock.json

@@ -24,7 +24,7 @@
 		"autoprefixer": "^10.4.21",
 		"chokidar": "^4.0.3",
 		"cssnano": "^7.1.0",
-		"postcss": "^8.5.6",
+		"postcss": "^8.5.12",
 		"prettier": "^3.6.2",
 		"rtlcss": "^4.3.0",
 		"sass": "^1.90.0",