Bump cssnano from 5.1.0 to 5.1.1

Bumps [cssnano](https://github.com/cssnano/cssnano) from 5.1.0 to 5.1.1.
- [Release notes](https://github.com/cssnano/cssnano/releases)
- [Commits](https://github.com/cssnano/cssnano/compare/cssnano@5.1.0...cssnano@5.1.1)

---
updated-dependencies:
- dependency-name: cssnano
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

package.json

@@ -13,7 +13,7 @@
     "@lodder/grunt-postcss": "3.1.1",
     "@squoosh/cli": "0.7.2",
     "autoprefixer": "10.4.2",
-    "cssnano": "5.1.0",
+    "cssnano": "5.1.1",
     "grunt": "1.4.1",
     "grunt-cli": "1.4.3",
     "grunt-concurrent": "3.0.0",