Bump postcss-loader from 7.3.4 to 8.0.0 in /webapp (#489)

Bumps [postcss-loader](https://github.com/webpack-contrib/postcss-loader) from 7.3.4 to 8.0.0.
- [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...v8.0.0)

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

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

webapp/package.json

@@ -6,7 +6,7 @@
     "autoprefixer": "^10.4.12",
     "daisyui": "^4.0.1",
     "postcss": "^8.4.16",
-    "postcss-loader": "^7.0.1",
+    "postcss-loader": "^8.0.0",
     "tailwindcss": "^3.1.8"
   }
 }