chore(package): update eslint-plugin-promise to version 4.2.1

Closes #80

Author: greenkeeper[bot]

package.json

@@ -50,7 +50,7 @@
     "eslint-config-standard": "11.0.0",
     "eslint-plugin-import": "2.12.0",
     "eslint-plugin-node": "6.0.1",
-    "eslint-plugin-promise": "4.0.0",
+    "eslint-plugin-promise": "4.2.1",
     "eslint-plugin-standard": "4.0.0",
     "jscpd": "0.6.22",
     "lokka": "1.7.0",