Merge pull request #693 from textpattern/dependabot/npm_and_yarn/postcss-8.5.6

Bump postcss from 8.5.3 to 8.5.6

Author: petecooper

package.json

@@ -25,7 +25,7 @@
     "grunt-stylelint": "0.20.1",
     "grunt-terser": "2.0.0",
     "load-grunt-tasks": "5.1.0",
-    "postcss": "8.5.3",
+    "postcss": "8.5.6",
     "sass": "1.86.1",
     "stylelint": "16.16.0",
     "stylelint-config-standard-scss": "15.0.1",