Merge pull request #858 from textpattern/dependabot/npm_and_yarn/grunt-stylelint-0.21.0

Bump grunt-stylelint from 0.20.1 to 0.21.0

Author: petecooper

package.json

@@ -21,7 +21,7 @@
     "grunt-contrib-watch": "1.1.0",
     "grunt-replace-regex": "1.0.3",
     "grunt-sass": "4.1.0",
-    "grunt-stylelint": "0.20.1",
+    "grunt-stylelint": "0.21.0",
     "grunt-terser": "2.0.0",
     "load-grunt-tasks": "5.1.0",
     "sass": "1.91.0",