chore(package): update rollup to version 2.3.4

Closes #19

Author: greenkeeper[bot]

package.json

@@ -72,7 +72,7 @@
     "prompt": "^1.0.0",
     "replace-in-file": "^4.1.3",
     "rimraf": "^3.0.0",
-    "rollup": "^1.25.1",
+    "rollup": "^2.3.4",
     "rollup-plugin-commonjs": "^10.1.0",
     "rollup-plugin-json": "^4.0.0",
     "rollup-plugin-node-resolve": "^5.2.0",