npm: bump postcss-preset-env from 6.7.0 to 7.8.2

Bumps [postcss-preset-env](https://github.com/csstools/postcss-plugins/tree/HEAD/plugin-packs/postcss-preset-env) from 6.7.0 to 7.8.2.
- [Release notes](https://github.com/csstools/postcss-plugins/releases)
- [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>

package.json

@@ -107,7 +107,7 @@
  "lint-staged": "^10.0.10",
  "next-router-mock": "^0.6.7",
  "postcss": "^8.4.12",
- "postcss-preset-env": "^6.7.0",
+ "postcss-preset-env": "^7.8.2",
  "prettier": "^2.0.2",
  "tailwindcss": "^3.0.23",
  "twin.macro": "^2.4.0",