Bump underscore from 1.13.6 to 1.13.8 in /lib/ts

Bumps [underscore](https://github.com/jashkenas/underscore) from 1.13.6 to 1.13.8.
- [Commits](https://github.com/jashkenas/underscore/compare/1.13.6...1.13.8)

---
updated-dependencies:
- dependency-name: underscore
  dependency-version: 1.13.8
  dependency-type: indirect
...

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