chore(package): update eslint to version 6.7.2

Closes #583

Author: greenkeeper[bot]

package.json

@@ -24,7 +24,7 @@
         "chai": "4.2.0",
         "chai-spies": "1.0.0",
         "coveralls": "3.0.3",
-        "eslint": "5.16.0",
+        "eslint": "6.7.2",
         "espree": "5.0.1",
         "gulp": "4.0.2",
         "gulp-eslint": "5.0.0",