chore(package): update rollup to version 0.64.1

Closes #25

Author: greenkeeper[bot]

package.json

@@ -59,7 +59,7 @@
     "react-dom": "^16.4.1",
     "react-test-renderer": "^16.4.1",
     "regenerator-runtime": "^0.12.0",
-    "rollup": "^0.63.5",
+    "rollup": "^0.64.1",
     "rollup-plugin-babel": "^3.0.7",
     "rollup-plugin-commonjs": "^9.1.0",
     "rollup-plugin-json": "^3.0.0",