Bump autoprefixer to 10.4.21

Author: oliverhaagh

package.json

@@ -14,7 +14,7 @@
   },
   "devDependencies": {
     "@types/bootstrap": "^5.2.6",
-    "autoprefixer": "^10.4.14",
+    "autoprefixer": "^10.4.21",
     "css-loader": "^7.0.0",
     "html-webpack-plugin": "^5.6.4",
     "gh-pages": "^6.3.0",