Update dependency css-loader to v3

Author: renovate-bot

package-lock.json

@@ -26,7 +26,7 @@
 		"classnames": "2.2.6",
 		"copy-webpack-plugin": "5.0.3",
 		"cross-env": "5.2.0",
-		"css-loader": "2.1.1",
+		"css-loader": "3.1.0",
 		"eslint": "6.1.0",
 		"exports-loader": "0.7.0",
 		"file-loader": "4.1.0",