Bump postcss-loader from 6.2.1 to 7.0.1

Bumps [postcss-loader](https://github.com/webpack-contrib/postcss-loader) from 6.2.1 to 7.0.1.
- [Release notes](https://github.com/webpack-contrib/postcss-loader/releases)
- [Changelog](https://github.com/webpack-contrib/postcss-loader/blob/master/CHANGELOG.md)
- [Commits](webpack-contrib/postcss-loader@v6.2.1...v7.0.1)

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

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

package.json

@@ -60,7 +60,7 @@
     "null-loader": "^4.0.1",
     "postcss": "^8.4.8",
     "postcss-import": "^15.0.0",
-    "postcss-loader": "^6.2.1",
+    "postcss-loader": "^7.0.1",
     "postcss-preset-env": "^7.8.2",
     "raw-loader": "^4.0.2",
     "react-select": "^5.4.0",