build(deps-dev): bump eslint from 6.8.0 to 7.5.0 in /frontend (#575)

Bumps [eslint](https://github.com/eslint/eslint) from 6.8.0 to 7.5.0.
- [Release notes](https://github.com/eslint/eslint/releases)
- [Changelog](https://github.com/eslint/eslint/blob/master/CHANGELOG.md)
- [Commits](eslint/eslint@v6.8.0...v7.5.0)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

frontend/package.json

@@ -27,7 +27,7 @@
     "babel-polyfill": "^6.26.0",
     "clean-webpack-plugin": "^3.0.0",
     "css-loader": "^3.0.0",
-    "eslint": "^6.2.2",
+    "eslint": "^7.5.0",
     "eslint-config-prettier": "^6.2.0",
     "eslint-config-standard": "^14.1.0",
     "eslint-loader": "^4.0.0",