Update dependency css-loader to v5

Author: renovate-bot

package-lock.json

@@ -29,7 +29,7 @@
     "babel-loader": "^8.0.6",
     "clean-webpack-plugin": "^3.0.0",
     "copy-webpack-plugin": "^5.0.4",
-    "css-loader": "^2.1.1",
+    "css-loader": "^5.0.1",
     "grafana-sdk-mocks": "github:grafana/grafana-sdk-mocks",
     "style-loader": "^1.0.0",
     "webpack": "^4.32.2",