Update devDependencies

[See current devDependencies on David DM](https://david-dm.org/ModelN/backbone.subroute#info=devDependencies). Just updating them to the latest versions to turn that badge in the README green for you. Tested, and it works fine.

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**Changes:**
- Updated all `devDependencies` to latest versions

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If you need anything else in this PR, please let me know. Thanks