fix ganache version
"license": "AGPL-3.0",
"devDependencies": {
"chai": "^4.1.2",
- "ganache-cli": "^6.1.8",
+ "ganache-cli": "6.1.8",
"openzeppelin-solidity": "1.12.0",
"truffle": "4.1.14",
"truffle-assertions": "^0.3.1"
