chore(package): update rollup-plugin-sourcemaps to version 0.6.2

Closes #39

Author: greenkeeper[bot]

package.json

@@ -48,7 +48,7 @@
     "prettier": "^2.0.0",
     "rimraf": "^3.0.0",
     "rollup": "^1.27.7",
-    "rollup-plugin-sourcemaps": "^0.4.2",
+    "rollup-plugin-sourcemaps": "^0.6.2",
     "ts-jest": "^23.1.4",
     "typescript": "^2.9.2",
     "uglify-js": "^3.4.8"