Bump extract-text-webpack-plugin from 3.0.0 to 3.0.2

Bumps [extract-text-webpack-plugin](https://github.com/webpack-contrib/extract-text-webpack-plugin) from 3.0.0 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@v3.0.0...v3.0.2)

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

package.json

@@ -21,7 +21,7 @@
     "eslint-plugin-import": "2.7.0",
     "eslint-plugin-jsx-a11y": "5.1.1",
     "eslint-plugin-react": "7.1.0",
-    "extract-text-webpack-plugin": "3.0.0",
+    "extract-text-webpack-plugin": "3.0.2",
     "file-loader": "0.11.2",
     "fs-extra": "3.0.1",
     "html-webpack-plugin": "2.29.0",