chore(package): update rollup to version 0.68.0

Author: greenkeeper[bot]

package.json

@@ -83,7 +83,7 @@
     "react-dom": "^16.6.3",
     "react-testing-library": "^5.3.2",
     "rimraf": "^2.6.2",
-    "rollup": "^0.67.4",
+    "rollup": "^0.68.0",
     "rollup-plugin-babel": "^4.1.0",
     "rollup-plugin-commonjs": "^9.2.0",
     "rollup-plugin-node-resolve": "^4.0.0",