fix: Remove useBuiltIns from babel config to fix warnings

Author: Andrey Okonetchnikov

.babelrc

@@ -5,8 +5,6 @@
 			"@babel/env",
 			{
 				"modules": false,
-				"useBuiltIns": "usage",
-				"corejs": 3
 			}
 		],
 		"@babel/react",

package.json

@@ -33,7 +33,6 @@
     "@emotion/styled": "^10.0.11",
     "@mdx-js/react": "^1.0.20",
     "clipboard-copy": "^3.0.0",
-    "core-js": "^3.1.3",
     "lodash": "^4.17.11",
     "polished": "^3.4.0",
     "prop-types": "^15.7.2",