chore(package): update rollup-plugin-sourcemaps to version 0.6.1

Closes #40

Author: greenkeeper[bot]

package.json

@@ -98,7 +98,7 @@
     "rollup": "^1.14.6",
     "rollup-plugin-commonjs": "^9.2.0",
     "rollup-plugin-node-resolve": "^4.2.4",
-    "rollup-plugin-sourcemaps": "^0.4.2",
+    "rollup-plugin-sourcemaps": "^0.6.1",
     "rollup-plugin-uglify": "3.0.0",
     "run-sequence": "^2.2.1",
     "rxjs": "^6.5.2",