housekeeping: non-breaking dependency changes (via npm audit) (#6068)

* cypress @3.8.3
* mocha @5.2.0
* json-merger @1.1.2

package.json

@@ -109,7 +109,7 @@
     "copy-webpack-plugin": "^5.1.1",
     "cors": "^2.8.5",
     "css-loader": "^3.1.0",
-    "cypress": "^3.4.1",
+    "cypress": "^3.8.3",
     "dedent": "^0.7.0",
     "deepmerge": "^2.1.0",
     "enzyme": "^2.7.1",
@@ -126,12 +126,12 @@
     "imports-loader": "^0.8.0",
     "jsdom": "^11.10.0",
     "json-loader": "^0.5.7",
-    "json-merger": "^1.1.1",
+    "json-merger": "^1.1.2",
     "json-server": "^0.16.0",
     "less": "^3.9.0",
     "license-checker": "^19.0.0",
     "mini-css-extract-plugin": "^0.9.0",
-    "mocha": "^5.1.1",
+    "mocha": "^5.2.0",
     "nightwatch": "^1.3.4",
     "node-sass": "^4.13.1",
     "npm-audit-ci-wrapper": "^2.3.0",