build(deps-dev): Update terser-webpack-plugin requirement in /frontend (#153)

Updates the requirements on [terser-webpack-plugin](https://github.com/webpack-contrib/terser-webpack-plugin) to permit the latest version.
- [Release notes](https://github.com/webpack-contrib/terser-webpack-plugin/releases)
- [Changelog](https://github.com/webpack-contrib/terser-webpack-plugin/blob/master/CHANGELOG.md)
- [Commits](webpack-contrib/terser-webpack-plugin@v1.3.0...v2.0.1)

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

Author: dependabot-preview[bot]

frontend/package.json

@@ -41,7 +41,7 @@
     "optimize-css-assets-webpack-plugin": "^5.0.3",
     "prettier": "1.18.2",
     "standard": "^14.1.0",
-    "terser-webpack-plugin": "^1.3.0",
+    "terser-webpack-plugin": "^2.0.1",
     "webpack": "^4.35.3",
     "webpack-cli": "^3.3.6",
     "webpack-dev-server": "^3.7.2",