chore(package): downgraded again rollup-plugin-uglify to v3 due to a bug

Author: AnthonyNahas

package-lock.json

@@ -100,7 +100,7 @@
     "rollup-plugin-commonjs": "9.1.3",
     "rollup-plugin-node-resolve": "3.3.0",
     "rollup-plugin-sourcemaps": "0.4.2",
-    "rollup-plugin-uglify": "4.0.0",
+    "rollup-plugin-uglify": "3.0.0",
     "run-sequence": "2.2.1",
     "rxjs": "6.1.0",
     "sass-loader": "7.0.1",