Merge pull request #891 from textpattern/dependabot/npm_and_yarn/cssnano-8.0.6

Bump cssnano from 8.0.5 to 8.0.6

Author: petecooper

package.json

@@ -11,7 +11,7 @@
   "devDependencies": {
     "@lodder/grunt-postcss": "3.1.1",
     "autoprefixer": "10.5.4",
-    "cssnano": "8.0.5",
+    "cssnano": "8.0.6",
     "grunt": "1.6.3",
     "grunt-cli": "1.5.0",
     "grunt-concurrent": "3.0.0",