Bump css-loader from 3.2.1 to 5.2.6

Bumps [css-loader](https://github.com/webpack-contrib/css-loader) from 3.2.1 to 5.2.6.
- [Release notes](https://github.com/webpack-contrib/css-loader/releases)
- [Changelog](https://github.com/webpack-contrib/css-loader/blob/master/CHANGELOG.md)
- [Commits](webpack/css-loader@v3.2.1...v5.2.6)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

package-lock.json

@@ -75,7 +75,7 @@
     "babel-preset-stage-3": "^6.24.1",
     "copy-webpack-plugin": "^5.0.4",
     "core-js": "^3.2.1",
-    "css-loader": "^3.2.0",
+    "css-loader": "^5.2.6",
     "es6-promise": "^4.2.4",
     "file-loader": "^4.2.0",
     "fs-extra": "^8.1.0",