Bump core-js from 3.4.5 to 3.4.7

Bumps [core-js](https://github.com/zloirock/core-js) from 3.4.5 to 3.4.7.
- [Release notes](https://github.com/zloirock/core-js/releases)
- [Changelog](https://github.com/zloirock/core-js/blob/master/CHANGELOG.md)
- [Commits](zloirock/core-js@v3.4.5...v3.4.7)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

package.json

@@ -21,7 +21,7 @@
   },
   "dependencies": {
     "babel-plugin-transform-class-properties": "6.24.1",
-    "core-js": "3.4.5"
+    "core-js": "3.4.7"
   },
   "devDependencies": {
     "@babel/cli": "7.7.5",