Bump postcss-loader from 7.3.4 to 8.1.0 (#2502)

Bumps [postcss-loader](https://github.com/webpack-contrib/postcss-loader) from 7.3.4 to 8.1.0.
- [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@v7.3.4...v8.1.0)

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

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

package.json

@@ -117,7 +117,7 @@
     "numeral": "~2.0.6",
     "popper.js": "~1.16.1",
     "postcss": "~8.4.33",
-    "postcss-loader": "~7.3.4",
+    "postcss-loader": "~8.1.0",
     "postcss-normalize": "~10.0.1",
     "prettier": "~3.2.2",
     "prop-types": "~15.8.1",