Bump wagtail-factories from 2.1.0 to 4.0.0 in /app

Bumps [wagtail-factories](https://github.com/wagtail/wagtail-factories) from 2.1.0 to 4.0.0.
- [Release notes](https://github.com/wagtail/wagtail-factories/releases)
- [Changelog](https://github.com/wagtail/wagtail-factories/blob/main/CHANGES)
- [Commits](wagtail/wagtail-factories@2.1.0...4.0.0)

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

app/poetry.lock

@@ -37,7 +37,7 @@ boto = "^2.49.0"
 rollbar = "^0.16.1"
 black = "^20.8b1"
 typed-ast = "^1.5.0" # required only if black < 21.10b0
-wagtail_factories = "^2.0.1"
+wagtail_factories = "^4.0.0"
 beautifulsoup4 = "^4.8.2"
 django-basic-auth-ip-whitelist = "^0.3.4"
 lxml = "^4.6.3"