Update extract-text-webpack-plugin requirement to 3.0.2 in /services/client

Updates the requirements on [extract-text-webpack-plugin](https://github.com/webpack-contrib/extract-text-webpack-plugin) to permit the latest version.
- [Release notes](https://github.com/webpack-contrib/extract-text-webpack-plugin/releases)
- [Changelog](https://github.com/webpack-contrib/extract-text-webpack-plugin/blob/master/CHANGELOG.md)
- [Commits](https://github.com/webpack-contrib/extract-text-webpack-plugin/commits/v3.0.2)

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

Author: dependabot-support

services/client/package.json

@@ -62,7 +62,7 @@
     "eslint-plugin-jsx-a11y": "6.0.3",
     "eslint-plugin-prettier": "2.6.0",
     "eslint-plugin-react": "7.7.0",
-    "extract-text-webpack-plugin": "3.0.0",
+    "extract-text-webpack-plugin": "3.0.2",
     "fs-extra": "^5.0.0",
     "node-sass": "^4.5.3",
     "prettier": "1.10.2",