chore(deps): update dependency rollup to ^0.68.0 [security]

Author: renovate[bot]

package.json

@@ -67,7 +67,7 @@
     "lint-staged": "^8.0.4",
     "mocha": "^5.2.0",
     "rimraf": "^2.6.2",
-    "rollup": "^0.57.1",
+    "rollup": "^0.68.0",
     "rollup-plugin-buble": "^0.16.0",
     "rollup-plugin-commonjs": "^8.0.2",
     "rollup-plugin-node-resolve": "^3.0.0",