Update npm packages used (terser instead of uglify, in particular)

Author: dpvc

package.json

@@ -6,11 +6,11 @@
     "mathjax-full": "^3.1.0"
   },
   "devDependencies": {
-    "@babel/core": "^7.10.4",
-    "@babel/preset-env": "^7.10.4",
+    "@babel/core": "^7.11.1",
+    "@babel/preset-env": "^7.11.0",
     "babel-loader": "^8.1.0",
-    "uglifyjs-webpack-plugin": "^2.2.0",
-    "webpack": "^4.43.0",
+    "terser-webpack-plugin": "^4.1.0",
+    "webpack": "^4.44.1",
     "webpack-cli": "^3.3.12"
   },
   "scripts": {