chore(package): update solidity-coverage to version 0.7.5

Closes #16

Author: greenkeeper[bot]

package.json

@@ -11,7 +11,7 @@
   "devDependencies": {
     "ganache-cli": "^6.0.3",
     "mocha": "^5.0.0",
-    "solidity-coverage": "^0.5.0",
+    "solidity-coverage": "^0.7.5",
     "truffle": "^4.1.3",
     "solium": "^1.1.3",
     "truffle-hdwallet-provider": "0.0.3",