chore(package): update rollup to version 2.10.9

Closes #98

Author: greenkeeper[bot]

package.json

@@ -48,7 +48,7 @@
     "npm-run-all": "^4.0.2",
     "opener": "^1.4.1",
     "rimraf": "^3.0.0",
-    "rollup": "^1.29.1",
+    "rollup": "^2.10.9",
     "rollup-plugin-buble": "^0.19.2",
     "sinon": "^8.0.0",
     "strip-json-comments-cli": "^1.0.1",