[Dev Deps] loosen the core-js dep

 - v2.4.1 has a bug in its TypedArray polyfill

Author: ljharb

package.json

@@ -5,7 +5,7 @@
   "main": "index.js",
   "devDependencies": {
     "@ljharb/eslint-config": "^16.0.0",
-    "core-js": "~2.4.1",
+    "core-js": "^2.5.7",
     "eslint": "^6.8.0",
     "nyc": "^10.3.2",
     "safe-publish-latest": "^1.1.4",