Merge pull request #1223 from textpattern/dependabot/npm_and_yarn/postcss-8.5.9

Bump postcss from 8.5.8 to 8.5.9

Author: petecooper

package.json

@@ -22,7 +22,7 @@
     "cross-env": "10.1.0",
     "css-loader": "7.1.4",
     "mini-css-extract-plugin": "2.10.2",
-    "postcss": "8.5.8",
+    "postcss": "8.5.9",
     "postcss-loader": "8.2.1",
     "postcss-scss": "4.0.9",
     "sass": "1.99.0",