fix(package): update core-js to version 3.0.0

Author: greenkeeper[bot]

package.json

@@ -24,7 +24,7 @@
   },
   "homepage": "https://github.com/toxic-johann/git-prefix-tag#readme",
   "dependencies": {
-    "core-js": "^2.5.3",
+    "core-js": "^3.0.0",
     "semver": "^5.5.0",
     "shelljs": "^0.8.1",
     "toxic-predicate-functions": "^0.2.3"