Update package.json

package.json

@@ -38,7 +38,7 @@
     "classnames": "2.2.6",
     "computed-style-to-inline-style": "3.0.0",
     "copy-webpack-plugin": "6.4.1",
-    "core-js": "3.23.3",
+    "core-js": "2.5.7",
     "css-loader": "^1.0.1",
     "es6-object-assign": "1.1.0",
     "file-loader": "2.0.0",
@@ -120,6 +120,7 @@
     "babel-eslint": "10.0.3",
     "babel-loader": "8.2.2",
     "chromedriver": "105.0.0",
+    "cross-env": "^7.0.3",
     "enzyme": "3.10.0",
     "enzyme-adapter-react-16": "1.3.0",
     "eslint": "5.16.0",