build(deps-dev): bump postcss-loader in /services/idp

Bumps [postcss-loader](https://github.com/webpack/postcss-loader) from 4.3.0 to 8.2.1.
- [Release notes](https://github.com/webpack/postcss-loader/releases)
- [Changelog](https://github.com/webpack/postcss-loader/blob/main/CHANGELOG.md)
- [Commits](https://github.com/webpack/postcss-loader/compare/v4.3.0...v8.2.1)

---
updated-dependencies:
- dependency-name: postcss-loader
  dependency-version: 8.2.1
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

services/idp/package.json

@@ -68,7 +68,7 @@
     "mini-css-extract-plugin": "2.9.2",
     "pnp-webpack-plugin": "1.7.0",
     "postcss-flexbugs-fixes": "5.0.2",
-    "postcss-loader": "4.3.0",
+    "postcss-loader": "8.2.1",
     "postcss-normalize": "13.0.1",
     "postcss-preset-env": "11.2.0",
     "react-dev-utils": "^12.0.1",