Bump terser-webpack-plugin to 4.2.3

Author: mwiencek

package.json

@@ -61,7 +61,7 @@
     "shelljs": "0.8.4",
     "sliced": "1.0.1",
     "tablesorter": "2.31.3",
-    "terser-webpack-plugin": "1.3.0",
+    "terser-webpack-plugin": "4.2.3",
     "webpack": "4.46.0",
     "webpack-cli": "3.3.12",
     "webpack-manifest-plugin": "2.0.4",