Upgrade ajv 6.5.4 -> 6.5.5

Author: ehmicky

package-lock.json

@@ -28,7 +28,7 @@
     "lib": "src"
   },
   "dependencies": {
-    "ajv": "^6.5.4",
+    "ajv": "^6.5.5",
     "chalk": "^2.4.1",
     "cli-truncate": "^1.1.0",
     "cross-fetch": "^2.2.3",