Bump extract-text-webpack-plugin from 1.0.1 to 3.0.2

Bumps [extract-text-webpack-plugin](https://github.com/webpack-contrib/extract-text-webpack-plugin) from 1.0.1 to 3.0.2.
- [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](webpack-contrib/extract-text-webpack-plugin@v1.0.1...v3.0.2)

Signed-off-by: dependabot[bot] <support@dependabot.com>

package.json

@@ -26,7 +26,7 @@
     "eslint-plugin-import": "^2.13.0",
     "eslint-plugin-jsx-a11y": "2.2.3",
     "eslint-plugin-react": "7.10.0",
-    "extract-text-webpack-plugin": "1.0.1",
+    "extract-text-webpack-plugin": "3.0.2",
     "file-loader": "0.9.0",
     "filesize": "3.3.0",
     "find-cache-dir": "2.0.0",