feat: add chainlink dependencies

Author: MerlinEgalite

package.json

@@ -55,6 +55,7 @@
   "dependencies": {
     "@kleros/kleros": "^0.1.2",
     "@realitio/realitio-contracts": "^2.0.5",
+    "@chainlink/contracts": "^0.1.7",
     "minimetoken": "^0.2.0",
     "openzeppelin-solidity": "^1.12.0",
     "web3-utils": "^1.2.1"