Bump wagtailmenus from 3.1.9 to 4.0

Bumps [wagtailmenus](https://github.com/jazzband/wagtailmenus) from 3.1.9 to 4.0.
- [Release notes](https://github.com/jazzband/wagtailmenus/releases)
- [Changelog](https://github.com/jazzband/wagtailmenus/blob/master/CHANGELOG.md)
- [Commits](jazzband/wagtailmenus@v3.1.9...v4.0.0)

---
updated-dependencies:
- dependency-name: wagtailmenus
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

requirements/base.txt

@@ -36,7 +36,7 @@ wagtail-django-recaptcha==1.0
 
 # Wagtail Menu
 # ------------------------------------------------------------------------------
-wagtailmenus==3.1.9
+wagtailmenus==4.0
 
 # Wagtail Localize
 # ------------------------------------------------------------------------------