chore(package): update cross-env to version 6.0.2

Closes #69

Author: greenkeeper[bot]

Diff for: package.json

@@ -14,7 +14,7 @@
     "angular-mocks": "^1.7.8",
     "angularjs-testbed": "^0.3.3",
     "copyfiles": "2.1.0",
-    "cross-env": "5.2.0",
+    "cross-env": "6.0.2",
     "css-loader": "2.1.1",
     "file-loader": "3.0.1",
     "fork-ts-checker-webpack-plugin": "^1.3.3",