Bump backbone from 1.6.0 to 1.6.1 in /job-dsl-plugin (#1538)

Author: dependabot[bot]

job-dsl-plugin/package-lock.json

@@ -18,7 +18,7 @@
   },
   "license": "Apache-2.0",
   "dependencies": {
-    "backbone": "1.6.0",
+    "backbone": "1.6.1",
     "backbone.marionette": "4.1.3",
     "bootstrap": "3.4.1",
     "highlight.js": "11.11.1",