Bump core-js from 3.1.2 to 3.1.3 in /terminus-core
Bump core-js from 3.1.2 to 3.1.3 in /terminus-core

Bumps [core-js](https://github.com/zloirock/core-js) from 3.1.2 to 3.1.3.
- [Release notes](https://github.com/zloirock/core-js/releases)
- [Changelog](https://github.com/zloirock/core-js/blob/master/CHANGELOG.md)
- [Commits](https://github.com/zloirock/core-js/compare/v3.1.2...v3.1.3)
Eugeny/terminus,Eugeny/terminus,Eugeny/terminus,Eugeny/terminus,Eugeny/terminus,Eugeny/terminus