Merge pull request #761 from textpattern/dependabot/npm_and_yarn/postcss-8.5.13

Bump postcss from 8.5.12 to 8.5.13

Author: petecooper

package.json

@@ -25,7 +25,7 @@
     "grunt-stylelint": "0.21.0",
     "grunt-terser": "2.0.0",
     "load-grunt-tasks": "5.1.0",
-    "postcss": "8.5.12",
+    "postcss": "8.5.13",
     "sass": "1.99.0",
     "stylelint": "17.9.1",
     "stylelint-config-standard-scss": "17.0.0",