chore(deps): bump cssnano from 5.1.15 to 6.0.0 (#618)

Bumps [cssnano](https://github.com/cssnano/cssnano) from 5.1.15 to 6.0.0.
- [Release notes](https://github.com/cssnano/cssnano/releases)
- [Commits](https://github.com/cssnano/cssnano/compare/cssnano@5.1.15...cssnano@6.0.0)

---
updated-dependencies:
- dependency-name: cssnano
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

package.json

@@ -67,7 +67,7 @@
         "codemirror": "^5.65.7",
         "concurrently": "^8.0.1",
         "coveralls": "^3.1.1",
-        "cssnano": "^5.1.12",
+        "cssnano": "^6.0.0",
         "escape-string-regexp": "^5.0.0",
         "eslint": "^8.19.0",
         "eslint-config-prettier": "^8.5.0",

packages/webpack-atomizer-loader/package.json

@@ -23,7 +23,7 @@
     "license": "MIT",
     "dependencies": {
         "atomizer": "^3.22.0",
-        "cssnano": "^5.0.7",
+        "cssnano": "^6.0.0",
         "postcss": "^8.3.6"
     },
     "repository": {