chore(package): update rollup to version 2.11.0

Closes #50

Author: greenkeeper[bot]

package.json

@@ -90,7 +90,7 @@
     "postcss-strip-inline-comments": "0.1.5",
     "pump": "3.0.0",
     "raw-loader": "1.0.0",
-    "rollup": "^1.7.4",
+    "rollup": "^2.11.0",
     "rollup-plugin-commonjs": "^9.2.2",
     "rollup-plugin-node-resolve": "^4.0.1",
     "rollup-plugin-sourcemaps": "0.4.2",