Bump eslint from 6.8.0 to 7.4.0 in /token-swap/js (#109)

Bumps [eslint](https://github.com/eslint/eslint) from 6.8.0 to 7.4.0.
- [Release notes](https://github.com/eslint/eslint/releases)
- [Changelog](https://github.com/eslint/eslint/blob/master/CHANGELOG.md)
- [Commits](eslint/eslint@v6.8.0...v7.4.0)

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

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

Author: dependabot[bot]

token-swap/js/package.json

@@ -49,7 +49,7 @@
     "buffer-layout": "^1.2.0",
     "css-loader": "^3.1.0",
     "dotenv": "8.2.0",
-    "eslint": "^6.1.0",
+    "eslint": "^7.4.0",
     "eslint-loader": "^4.0.2",
     "eslint-plugin-import": "^2.13.0",
     "eslint-plugin-react": "^7.11.1",