Bump underscore from 1.4.4 to 1.13.6

Bumps [underscore](https://github.com/jashkenas/underscore) from 1.4.4 to 1.13.6.
- [Release notes](https://github.com/jashkenas/underscore/releases)
- [Commits](jashkenas/underscore@1.4.4...1.13.6)

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

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Author: dependabot[bot]