Bump rlp from 2.0.0 to 2.2.4

Bumps [rlp](https://github.com/ethereumjs/rlp) from 2.0.0 to 2.2.4.
- [Release notes](https://github.com/ethereumjs/rlp/releases)
- [Changelog](https://github.com/ethereumjs/rlp/blob/master/CHANGELOG.md)
- [Commits](ethereumjs/rlp@2.0.0...v2.2.4)

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

Author: dependabot-preview[bot]

package-lock.json

@@ -189,7 +189,7 @@
     "redux": "4.0.4",
     "redux-actions": "2.6.5",
     "redux-thunk": "2.3.0",
-    "rlp": "2.0.0",
+    "rlp": "2.2.4",
     "scryptsy": "2.1.0",
     "solc": "ngotchac/solc-js",
     "store": "2.0.12",