Update dependency gulp to v3.9.1

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
gulp (source)	devDependencies	minor	3.8.11 -> 3.9.1

---

Release Notes

gulpjs/gulp

v3.9.1

Compare Source

• update interpret to 1.0.0 (support for babel-register)
• fix to include manpages in published tarball
• documentation/recipe updates

v3.9.0

Compare Source

• add babel support
• add transpiler fallback support
• add support for some renamed transpilers: livescript, etc
• add JSCS
• update dependencies (liftoff, interpret)
• documentation tweaks

---

Renovate configuration

:date: Schedule: At any time (no schedule defined).

:vertical_traffic_light: Automerge: Disabled by config. Please merge this manually once you are satisfied.

:recycle: Rebasing: Whenever PR becomes conflicted, or if you modify the PR title to begin with "rebase!".

:no_bell: Ignore: Close this PR and you won't be reminded about this update again.

---

• [ ] If you want to rebase/retry this PR, check this box

---

This PR has been generated by Renovate Bot. View repository job log here.