Merge pull request #539 from textpattern/dependabot/npm_and_yarn/postcss-8.4.19

Bump postcss from 8.4.8 to 8.4.19

Author: philwareham

package.json

@@ -26,7 +26,7 @@
     "grunt-stylelint": "0.16.0",
     "grunt-terser": "2.0.0",
     "load-grunt-tasks": "5.1.0",
-    "postcss": "8.4.8",
+    "postcss": "8.4.19",
     "sass": "1.49.9",
     "stylelint": "13.13.1",
     "stylelint-order": "4.1.0",