chore(deps-dev): bump css-loader from 6.7.3 to 6.8.1 (#6712)

Bumps [css-loader](https://github.com/webpack-contrib/css-loader) from 6.7.3 to 6.8.1.
- [Release notes](https://github.com/webpack-contrib/css-loader/releases)
- [Changelog](https://github.com/webpack-contrib/css-loader/blob/master/CHANGELOG.md)
- [Commits](https://github.com/webpack-contrib/css-loader/compare/v6.7.3...v6.8.1)

---
updated-dependencies:
- dependency-name: css-loader
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

package.json

@@ -17,7 +17,7 @@
     "codecov": "3.8.3",
     "comma-separated-values": "3.6.4",
     "copy-webpack-plugin": "11.0.0",
-    "css-loader": "6.7.3",
+    "css-loader": "6.8.1",
     "d3-axis": "3.0.0",
     "d3-scale": "3.3.0",
     "d3-selection": "3.0.0",