Bump wagtail-factories from 4.1.0 to 4.2.1

Bumps [wagtail-factories](https://github.com/wagtail/wagtail-factories) from 4.1.0 to 4.2.1.
- [Release notes](https://github.com/wagtail/wagtail-factories/releases)
- [Changelog](https://github.com/wagtail/wagtail-factories/blob/main/CHANGES)
- [Commits](wagtail/wagtail-factories@4.1.0...4.2.1)

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

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

requirements.txt

@@ -268,7 +268,7 @@ wagtail-ab-testing==0.9
     # via -r requirements.in
 wagtail-color-panel==1.5.0
     # via -r requirements.in
-wagtail-factories==4.1.0
+wagtail-factories==4.2.1
     # via -r requirements.in
 wagtail-footnotes @ git+https://github.com/MozillaFoundation/wagtail-footnotes.git@localized-footnotes
     # via -r requirements.in