Update cypress dep (tastejs#1988)

This version of Cypress is a year old now. Cypress has had a lot of updates since ~3.0.3, including a lot of performance improvements. [Full changelog](https://on.cypress.io/changelog#3-4-1)

Author: jennifer-shehane

package.json

@@ -30,7 +30,7 @@
     "bluebird": "^3.5.1",
     "chalk": "^2.3.0",
     "console.table": "^0.9.1",
-    "cypress": "^3.0.3",
+    "cypress": "^3.4.1",
     "del": "^0.1.1",
     "figlet": "^1.2.0",
     "gulp": "^3.9.0",