Bump cssnano from 7.0.6 to 7.1.0

Bumps [cssnano](https://github.com/cssnano/cssnano) from 7.0.6 to 7.1.0.
- [Release notes](https://github.com/cssnano/cssnano/releases)
- [Commits](https://github.com/cssnano/cssnano/compare/cssnano@7.0.6...cssnano@7.1.0)

---
updated-dependencies:
- dependency-name: cssnano
  dependency-version: 7.1.0
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

package.json

@@ -11,7 +11,7 @@
   "devDependencies": {
     "@lodder/grunt-postcss": "3.1.1",
     "autoprefixer": "10.4.21",
-    "cssnano": "7.0.6",
+    "cssnano": "7.1.0",
     "grunt": "1.6.1",
     "grunt-cli": "1.5.0",
     "grunt-concurrent": "3.0.0",