Bump postcss-loader in /web/modules/custom/react_tools/tools

Bumps [postcss-loader](https://github.com/webpack-contrib/postcss-loader) from 4.0.3 to 4.2.0.
- [Release notes](https://github.com/webpack-contrib/postcss-loader/releases)
- [Changelog](https://github.com/webpack-contrib/postcss-loader/blob/master/CHANGELOG.md)
- [Commits](webpack/postcss-loader@v4.0.3...v4.2.0)

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Author: dependabot[bot]

web/modules/custom/react_tools/tools/package-lock.json

@@ -48,7 +48,7 @@
     "pnp-webpack-plugin": "1.6.4",
     "postcss": "^8.0.0",
     "postcss-flexbugs-fixes": "5.0.2",
-    "postcss-loader": "^4.0.3",
+    "postcss-loader": "^4.2.0",
     "postcss-normalize": "9.0.0",
     "postcss-preset-env": "6.7.0",
     "postcss-safe-parser": "5.0.2",