Bump postcss-preset-env in /{{cookiecutter.project_slug}} (#4437)

Bumps [postcss-preset-env](https://github.com/csstools/postcss-plugins/tree/HEAD/plugin-packs/postcss-preset-env) from 8.5.1 to 9.0.0.
- [Changelog](https://github.com/csstools/postcss-plugins/blob/main/plugin-packs/postcss-preset-env/CHANGELOG.md)
- [Commits](https://github.com/csstools/postcss-plugins/commits/HEAD/plugin-packs/postcss-preset-env)

---
updated-dependencies:
- dependency-name: postcss-preset-env
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

{{cookiecutter.project_slug}}/package.json

@@ -25,7 +25,7 @@
     "pixrem": "^5.0.0",
     "postcss": "^8.3.11",
     "postcss-loader": "^7.0.2",
-    "postcss-preset-env": "^8.0.1",
+    "postcss-preset-env": "^9.0.0",
     "sass": "^1.43.4",
     "sass-loader": "^13.2.0",
     "webpack": "^5.65.0",