Bump cssnano from 7.1.2 to 7.1.3 (#983)

Bumps [cssnano](https://github.com/cssnano/cssnano) from 7.1.2 to 7.1.3.
- [Release notes](https://github.com/cssnano/cssnano/releases)
- [Commits](https://github.com/cssnano/cssnano/compare/cssnano@7.1.2...cssnano@7.1.3)

---
updated-dependencies:
- dependency-name: cssnano
  dependency-version: 7.1.3
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

package.json

@@ -28,7 +28,7 @@
     "@lodder/grunt-postcss": "3.1.1",
     "autoprefixer": "10.4.27",
     "babelify": "10.0.0",
-    "cssnano": "7.1.2",
+    "cssnano": "7.1.3",
     "grunt": "1.6.1",
     "grunt-browserify": "6.0.0",
     "grunt-cli": "1.5.0",